tag:blogger.com,1999:blog-5816896832759242962024-02-18T22:46:01.286-08:00Soil Testing EquipmentVarious references of Material Testing Equipment and Geotechnical products and procedures manual for the laboratory equipment of civil engineeringmayaisjakahttp://www.blogger.com/profile/11820472336428156095noreply@blogger.comBlogger18125tag:blogger.com,1999:blog-581689683275924296.post-4579470854732015172010-10-26T21:14:00.000-07:002010-10-26T21:17:40.130-07:00Standard Test Procedures Manual - WET TRACK ABRASION TEST<span style="font-weight: bold;">1. SCOPE</span><br />
<span style="font-weight: bold;"><br />
1.1. Description of Test</span><br />
This method covers measurement of the wearing qualities of slurry seal, hot sand asphaltmix and sulphur mixes under wet abrasion conditions.<br />
<br />
<span style="font-weight: bold;">2. APPARATUS AND MATERIALS</span><br />
<span style="font-weight: bold;"><br />
2.1. Equipment Required</span><br />
<div style="text-align: justify;">Balance 5000 g ± 1 g.<br />
Sieves - Canadian Metric Standard square mesh of size numbers as required by the specifications for the materials being tested. Oven - thermostatically controlled at 60oC ± 1o.<br />
Model C-100 Hobart mixer or equivalent. Metal tray 264 mm by 267 mm by 57 mm deep fitted with four vertical pins near the corners for holding template, sample and distilled water. Template 6 mm thick by 241 mm square with a centre hole 216 mm in diameter complete with four holes in corners to match pins in container tray. 22 to 27 kg grade asphalt roll roofing paper, 240 mm square with four holes to fit pins in metal tray. Water bath thermostatically controlled at 25o C ± 1o.<br />
<br />
Abrasive head weighing 2.27 kg coupled to the Hobart mixer with approximately 14 mm free up and down movement in the shaft sleeve. A section of 300 psi reinforced rubber hose 14 mm ID by 31 mm OD and 127 mm in length shall be mounted horizontally on the abrasive head as shown in ASTM Method D3910. Plywood base 305 mm square for transporting and drying of sample in template in the oven.<span style="font-weight: bold;"></span><br />
<br />
Suitable prop block and spacers for supporting platform assembly in position during testing. Mixing pan, soft brush, spatula, graduated cylinder, 1800 ml beaker and distilled water. Squeegee or straight edge 305 mm in length. Fumehood, hot plate. Hydraulic press. Steel plate 255 mm square and a 215 mm diameter steel disk, both about 10 mm thick to hold sample while forming in press.<br />
<br />
<span style="font-weight: bold;">3. PROCEDURE</span><br />
<span style="font-weight: bold;"><br />
3.1. Sample Preparation</span><br />
<span style="font-weight: bold;">3.1.1. Slurry</span><br />
<br />
Air dry aggregate similar to stockpile average to be used on job. Riffle carefully and complete sieve analysis as per STP 206-1. Place template on roofing paper and tack coat opening with SS1 emulsion. Quarter sufficient amount of dry aggregate required. Weigh approximately 80 gm of aggregate into mixing bowl making sure it is uniformly distributed. Add the predetermined amount of water and mix until particles are uniformly wetted. Finally, add the predetermined amount of emulsion and mix for a period of not less than 1 minute and not more than 3 minutes. <br />
<br />
Note: the required water and emulsion content are determined by the consistency test method described in ASTM method paragraph 5.1. A flow of 2 to 3 cm is normally required. Immediately pour sample into template containing smooth roofing paper. Squeegee or straight edge slurry level with the top of the template with minimum amount of manipulation and scrape off excess material and discard<br />
<br />
Place specimen in oven at 60o C and dry to constant weight. This usually requires a minimum of 15 hours. Remove sample from oven and allow to cool at room temperature and remove template and weigh. After weighing, place sample in 25o C water bath for 60 to 75 minutes before doing abrasion test.<br />
<br />
<span style="font-weight: bold;">3.1.2. Hot Sand Asphalt Mix</span><br />
<br />
Dry aggregate and adjust gradation with filler as necessary. Heat aggregate and asphalt cement to desired temperature required and mix at the asphalt content required by the engineer (usually 8 to 12%). Cut square of roofing paper, place on steel plate. Apply tack coat of asphalt to roofing paper and place two template molds on top. Spread 800 g of mix in mold and strike off level with straight edge. Place steel disk over centre of template and place in hydraulic press under 4545 kg for 5 minutes. Weigh mold, mix and paper. Place in oven at 60o C for 4 1/2 hours.<br />
After removing specimen from oven, place in water bath at 25o C for 1 1/2 hours.<br />
<br />
<span style="font-weight: bold;">3.1.3. Sulphur Mixes</span><br />
<br />
Dry aggregate and riffle sample to approximately 800 g required for testing. Select grade of asphalt cement and heat to approximately 135o C. Heat aggregate and asphalt to 135o C and mix at required asphalt content (usually 8%). Add pelletized sulphur to asphalt mixture based on weight of total mix. This usually requires 16-17% sulphur when the asphalt used is 8 to 8.5 percent range.<br />
<br />
Mix well under fume hood until the mixture becomes sloppy. Do not allow the temperature to exceed 150o C as the sulphur will combine with hydrogen to give off sulphur oxide gas. Cut square of roofing paper and place on steel plate. Apply tack coat of asphalt to roofing paper and place two mold plates on top. Spread sulphur mix in mold and strike off level with straight edge. Allow to cool at room temperature for 24 hours and weigh. After curing, place in water bath for 1 1/2 hours<br />
<br />
3.2. Test Procedure<br />
Remove specimen, template and roofing paper from water bath and place in metal tray with four pins to secure sample in bottom of tray. Cover sample with 6 mm distilled water at room temperature. Secure metal tray on the Hobart mixer by means of clamps provided and attach the rubber hose abrasion head. Elevate the platform until the rubber hose contacts the surface of sample. This usually requires sufficient pressure for the pin to be at the midpoint of the slotted sleeve. Use prop block to support platform assembly during testing. Operate mixer for exactly 5 minutes ± 2 seconds, at low speed. Remove sample from metal tray and wash off debris using soft brush. Place washed sample at 60o C in oven and dry to constant weight. Remove from oven and allow to cool at room temperature and weigh.<br />
<br />
<span style="font-weight: bold;">4. RESULTS AND CALCULATIONS</span><br />
<br />
<span style="font-weight: bold;">4.1. Collection of Test Results</span><br />
<br />
Record original sample weight after molding and drying to constant weight.<br />
<span style="font-weight: bold;"><br />
4.2. Calculations</span><br />
<br />
Weigh sample after abrasion and dry to constant weight. Original sample weight minus final abraded weight multiplied by 32.9 expresses the loss in grams per meter square.<br />
(W1 - W2) x 32.9 = g/m2<br />
<br />
<span style="font-weight: bold;">4.3. Reporting Results</span><br />
<br />
Report the loss in g/m2.<br />
<br />
<span style="font-weight: bold;">5. ADDED INFORMATION</span><br />
<br />
<span style="font-weight: bold;">5.1. References</span><br />
<span style="font-weight: bold;">A.S.T.M. D3910</span><br />
<span style="font-weight: bold;">Saskatchewan Highway Technical Report #29.</span><br />
<br />
<span style="font-weight: bold;">5.2. General</span><br />
<br />
Slurry showing a loss of more than 800 g/m2 is not acceptable. For asphalt mixes, a loss of 400 g/m2 should not be exceeded. For sulphur mixes no values are available. When pouring sample into template, care should be taken to mix the material uniformly to avoid segregation. Rotate hose after completion of each test and replace if badly worn.<br />
<br />
<br />
<div style="font-style: italic; text-align: right;">Source : Saskatchewan Highways and Transportation</div></div>mayaisjakahttp://www.blogger.com/profile/11820472336428156095noreply@blogger.com7tag:blogger.com,1999:blog-581689683275924296.post-79032458761976058442010-06-01T21:22:00.000-07:002010-07-19T18:45:34.734-07:00Drilling Equipment and Operation - Drilling Muds and Completion Systems. Part 1<div style="color: black;"><b>Drilling Equipment and Operation - Drilling Muds and Completion Systems</b></div><div style="color: black;"><br />
</div><div style="color: black;"><b>A. Drilling Muds and Completion Systems</b></div><div style="color: black; text-align: center;"><br />
</div><div style="color: black; text-align: center;"><b> 1.1 FUNCTIONS OF DRILLING MUDS</b></div><div style="color: black;"><b><br />
</b></div><div style="color: black;"><b>1.1.1 Drilling Fluid Definitions and General Functions</b></div><div style="color: black; text-align: justify;">Results of research has shown that penetration rate and its response to weight on bit and rotary speed ishighly dependent on the hydraulic horsepower reaching the formation at the bit. Because the drilling fluid flowrate sets the system pressure losses and these pressure losses set the hydraulic horsepower across the bit, it can be concluded that the drilling fluid is as important in determining drilling costs as all other “controllable” variables combined. Considering these factors, an optimum drilling fluid is properly formulated so that the flow rate necessary to clean the hole results in the proper hydraulic horsepower to clean the bit for the weight and rotary speed imposed to give the lowest cost, provided that this combination of variables results in a stable borehole which penetrates the desired target. This definition incorporates and places in perspective the five major functions of a drilling fluid.<b></b></div><div style="color: black; text-align: justify;"><b><br />
</b></div><div style="color: black; text-align: justify;"><b>1.1.2 Cool and Lubricate the Bit and Drill String</b></div><div style="color: black; text-align: justify;">Considerable heat and friction is generated at the bit and between the drill string and wellbore during drilling operations. Contact between the drill string andwellbore can also create considerable torque during rotation and drag during trips. Circulating drilling fluid transports heat away from these frictional sites, reducing the chance of premature bitfailure and pipe damage. The drilling fluid also lubricates the bit tooth penetration through the bottom hole debris into the rock and serves as a lubricant between the wellbore and drill string, reducing torque and drag<b>.</b></div><div style="color: black; text-align: justify;"><b><br />
</b></div><div style="color: black; text-align: justify;"><b>1.1.3 </b><b>Clean the Bit and the Bottom of the Hole</b></div><div style="color: black; text-align: justify;">If the cuttings generated at the bit face are not immediately removed and started toward the surface, they will be ground very fine, stick to the bit,and in general retard effective penetration into uncut rock.</div><div style="color: black; text-align: justify;"><br />
</div><div style="color: black; text-align: justify;"><b>1.1.4 Suspend Solids and Transport Cuttings and Sloughings to the Surface</b></div><div style="color: black; text-align: justify;">Drilling fluids must have the capacity to suspend weight materials and drilled solids during connections, bittrips, and logging runs, or they will settle to the low side or bottom of the hole. Failure to suspend weight<br />
materials can result in a reduction in the drilling fluids density, which can lead to kicks and potential of a blowout. The drilling fluid must be capable of transporting cuttings out of the hole at a reasonable velocity that minimizes theirdisintegration and incorporation as drilled solids into the drilling fluid system and able to release<br />
the cuttings at the surface for efficient removal. Failure to adequately clean the hole or to suspend drilled solids can contribute to hole problems such as fill on bottom after a trip, hole pack-off, lost returns, differentially stuck pipe, and inability to reach bottom with logging tools. Factors influencing removal of cuttings and formation sloughings and solids suspension include.</div><div style="color: black; text-align: justify;"><br />
</div><div style="color: black; text-align: justify;">• Density of the solids<br />
• Density of the drilling fluid<br />
• Rheological properties of the drilling fluid<br />
• Annular velocity</div><div style="color: black; text-align: justify;">• Hole angle<br />
• Slip velocity of the cuttings or sloughings</div><div style="color: black; text-align: justify;"><br />
</div><div style="color: black; text-align: justify;"><b>1.1.5 Stabilize the Wellbore and Control Subsurface Pressures</b></div><div style="color: black; text-align: justify;">Borehole instability is a natural function of the unequal mechanical stresses and physical-chemical interactions and pressures created when supporting material and surfaces are exposed in the process of drilling a well. The drilling fluidmust overcome the tendency for the hole to collapse frommechanical failure or fromchemical interaction of the formation with the drilling fluid. The Earth’s pressure gradient at sea level is 0.465 psi/ft,<br />
which is equivalent to the height of a column of salt water with a density (1.07 SG) of 8.94 ppg.<br />
In most drilling areas, the fresh water plus the solids incorporated into the water from drilling subsurface formations is sufficient to balance the formationpressures.</div><div style="color: black; text-align: justify;"><br />
</div><div style="color: black; text-align: justify;">However, it is common to experience abnormallypressured formations that require high-density drilling fluids to control the formation pressures. Failure to control downhole pressures can result in aninflux of formation fluids, resulting inakick or blowout. Borehole stabilityis also maintained or enhanced by controlling the loss of filtrate to permeble formations and by careful control of the chemical composition of the drilling fluid. Most permeable formations have pore space openings too small to allow the passage of whole mud into the formation, but filtrate from the drilling fluid can enter the pore spaces. The rate at which the filtrate enters the formation depends on the pressure differential between the formation and the column of drilling fluid and the quality of the filter cake deposited on the formation face. </div><div style="color: black; text-align: justify;"><br />
</div><div style="color: black; text-align: justify;">Large volumes of drilling fluid filtrate and filtrates that are incompatible with the formation or formation fluids may destabilize the formation through hydration of shale and/or chemical interactions between components of the drilling fluid and the wellbore. Drilling fluids that produce low-quality or thick filter cakes may alsocause tight hole conditions, including stuck pipe, difficulty in running casing, and poor cement jobs</div><div style="color: black; text-align: justify;"><br />
</div><div style="color: black; text-align: justify;"><b>1.1.6 Assist in the Gathering of Subsurface Geological Data and Formation Evaluation</b></div><div style="color: black; text-align: justify;"><br />
</div><div style="color: black; text-align: justify;">Interpretation of surface geological data gathered through drilled cuttings, cores, and electrical logs is used to determine the commercial value of the zones penetrated. Invasion of these zones by the drilling fluid, its filtrate (oil or water) may mask or interfere with interpretation of data retrieved or prevent full commercial recovery of hydrocarbon.</div><div style="color: black; text-align: justify;"><br />
</div><div style="color: black; text-align: justify;"><b>1.1.7 Other Functions</b><br />
In addition to the functions previously listed, the drilling fluid should be environmentally acceptable to the area inwhich it is used. It should be noncorrosive to tubulars being used in the drilling and completion operations.<br />
Most importantly, the drilling fluid should not damage the productive formations that are penetrated. The functions described here are a fewof themost obvious functions of a drilling fluid. Proper application of drilling fluids is the key to successfully drilling in various environments.</div><div style="color: black; text-align: justify;"><br />
</div><div style="color: black; text-align: center;"><b> 1.1 CLASSIFICATION</b></div><div style="color: black; text-align: justify;"><br />
</div><div style="color: black; text-align: justify;">Ageneralized classification of drilling fluids can be based on theirfluid phase, alkalinity, dispersion, and type of chemicals used in the formulation and degrees of inhibition. In a broad sense, drilling fluids can be broken into five major categories.</div><div style="color: black; text-align: justify;"><br />
</div><div style="color: black; text-align: justify;"><b>1.2.1 Freshwater Muds—Dispersed Systems</b><br />
The pHvalue of low-pHmudsmay range from7.0 to 9.5. Low-pHmuds include spud muds, bentonite-treated muds, natural muds, phosphate treated muds, organicthinned muds (e.g., red muds, lignite muds, lignosulfonatemuds), and organic colloid–treatedmuds. In this case, the lack of salinity of the water phase and the addition of chemical dispersants dictate the inclusion of these fluids inthis broad category.</div><div style="color: black; text-align: justify;"><b>1.2.2 Inhibited Muds—Dispersed Systems</b><br />
These are water-base drilling muds that repress the hydration and dispersion of clays through the inclusion of inhibiting ions such as calcium and salt. There are essentially four types of inhibited muds: lime muds (high pH), gypsummuds (lowpH), seawatermuds (unsaturated saltwater muds, lowpH), and saturated saltwatermuds (lowpH).Newer-generation inhibited-dispersed fluids offer enhanced inhibitive performance and formation stabilization; these fluids include sodium silicate muds, formate brine-based fluids, and cationic polymer fluids.</div><div style="color: black; text-align: justify;"><br />
<b>1.2.3 Low Solids Muds—Nondispersed Systems</b><br />
These muds contain less than 3–6% solids by volume, weight less than 9.5 lb/gal, and may be fresh or saltwater based. The typical low-solid systems are selective flocculent, minimum-solids muds, beneficiated clay muds, and low-solids polymer muds. Most low-solids drilling fluids are composed ofwaterwith varying quantities of bentonite and a polymer. The difference among low-solid systems lies in the various actions of different polymers.</div><div style="color: black; text-align: justify;"><b>1.2.4 Non aqueous Fluids</b><br />
Invert Emulsions Invert emulsions are formed when one liquid isdis persed as small droplets in another liquidwith which the dispersed liquidis immiscible. Mutually immiscible fluids, such as water and oil, can be emulsified by shear and the addition of surfactants. The suspending liquid is called the continuous phase, and the droplets are called the dispersed or discontinuous phase. There are two types of emulsions used indrilling fluids: oil-in-water emulsions that have water as the continuous phase and oil as the dispersed phase and water-in-oil emulsions that have oil as the continuous phase andwater as the dispersed phase (i.e., invert emulsions) Oil-Base Muds (nonaqueous fluid [NAF]) Oil-base muds containoil (refined from crude such as diesel or synthetic-base oil) as the continuous phase and trace amounts of water as the dispersed phase. Oil-base muds generally contain less than 5% (by volume) water (which acts as a polar activator for organophilic clay), whereas invert emulsion fluids generally have more than 5% water in mud. Oil-base muds are usually a mixture of base oil, organophilic clay, and lignite or asphalt, and the filtrate is all oil.</div><div style="color: black; text-align: justify;"><br />
</div><div style="color: black; text-align: center;"><br />
</div><div style="color: black; text-align: center;"><b>1.3 TESTING OF DRILLING SYSTEMS </b></div><div style="color: black; text-align: center;"><br />
</div><div style="color: black; text-align: justify;">To properly control the hole cleaning, suspension, and filtration properties of a drilling fluid, testing of the fluid properties is done on a daily basis. Most tests are conducted at the rigsite, and procedures are set forth<br />
in the API RPB13B. Testing of water-based fluids and nonaqueous fluids can be similar, but variations of procedures occur due to the nature of the fluidbeing tested.</div><div style="color: black; text-align: justify;"><b>1.3.1 Water-Base Muds Testing</b><br />
To accurately determine the physical properties of water-based drilling fluids, examination of the fluid is required in a field laboratory setting. In many cases, this consists of a fewsimple tests conducted by the derrickman or mud Engineer at the rigsite. The procedures for conducting all routine drilling fluid testing can be found in the American Petroleum Institute’s API RPB13B.</div><div style="color: black; text-align: justify;"><br />
</div><div style="color: black; text-align: justify;">within ±0.1 lb/gal or ±0.5 lb/ftDensity Often referredto as themudweight,densitymay be expressedas pounds per gallon (lb/gal), pounds per cubic foot (lb/ft3), specific gravity (SG) or pressure gradient (psi/ft). Any instrument of sufficient accuracy 3 may be used. The mud balance is the instrument most commonly used. The weight of a mud cup attached to one end of the beam is balanced on the other end by a fixed counterweight<br />
and a rider free to move along a graduated scale. The density of the fluid isadirect reading from the scales located on both sides of the mud balance.</div><div style="color: black; text-align: justify;"><br />
</div><div style="color: black; text-align: justify;">Marsh Funnel Viscosity Mud viscosity is a measure of the mud’s resis- tance toflow.Theprimary function ofdrillingfluidviscosity is a to transport cuttings to the surface and suspend weighing materials. Viscosity must<br />
be high enough that the weighting material will remain suspended but low enough to permit sand and cuttings to settle out and entrained gas to escape at the surface. Excessive viscosity can create high pump pressure, which magnifies the swab or surge effect during tripping operations. The control of equivalent circulating density (ECD) is always a prime concern when managing the viscosity of a drilling fluid. The Marsh funnel is a rig site instrument used tomeasure funnel viscosity. The funnel isdimensioned so that by following standard procedures, the outflow time of 1 qt (946ml) of freshwater at a temperature of 70±5◦F is26±0.5 seconds A graduated cup is used as a receiver.</div><div style="color: black; text-align: justify;">Direct Indicating Viscometer This is a rotational type instrument powered by an electricmotor or by a hand crank .Mud is contained in the annular space between two cylinders. The outer cylinder or rotor sleeve is driven at a constant rotational velocity; its rotation in the mud produces a torque on the inner cylinder or bob. A torsion spring restrains the movement of the bob. A dial attached to the bob indicates its displacement on a direct reading scale. Instrument constraints have been adjusted</div><div style="color: black; text-align: justify;"><br />
</div><div style="color: black; text-align: justify;">so that plasticviscosity, apparent viscosity, and yield point are obtained by using readings from rotor sleeve speeds of 300 and 600 rpm. Plasticviscosity (PV) in centipoise is equal to the 600 rpm dial reading minus the 300 rpm dial reading. Yield point (YP), in pounds per 100 ft 2, is equal to the 300-rpm dial reading minus the plasticviscosity. Apparent viscosity in centipoise is equal to the 600-rpm reading, divided by two.</div><div style="color: black; text-align: justify;"><br />
</div><div style="color: black; text-align: justify;"><b>Gel Strength Gel </b>strength is a measure of the inter-particle forces and indicates the gelling thatwill occurwhen circulation is stopped. This property prevents the cuttings from setting in the hole. High pump pressure is generally required to “break” circulation inahigh-gel mud. Gel strength is measured inunits of lbf/100 ft 2.This reading is obtained by noting the maximum dial deflection when the rotational viscometer is turned at a low rotor speed (3 rpm) after the mud has remained static for some period of time (10 seconds, 10 minutes, or 30 minutes). If the mud is allowed to remain static in the viscometer for a period of 10 seconds, the maximum dial deflection obtainedwhen the viscometer is turned on is reported as the initial gel on the API mud report form. If the mud is allowed to remain static for 10minutes, themaximumdial deflection is reported as the 10-min gel. The same device is used to determine gel strength that is used to determine the plasticviscosity and yield point, the Variable Speed Rheometer/Viscometer. </div><div style="color: black; text-align: justify;"><br />
</div><div style="color: black; text-align: justify;"><b>API Filtration Astandard API filter press </b>is used to determine the filter cake building characteristics and filtration of a drilling fluid(Figure 1.4). TheAPI filter press consists of a cylindricalmud chambermade ofmaterials resistant to strongly alkaline solutions.Afilter paper is placed on the bottom of the chamber just above a suitable support. The total filtration area is 7.1 (±0.1) in. 2. Below the support is a drain tube for discharging the filtrate into a graduated cylinder. The entire assembly is supported by a stand so 100-psi pressure can be applied to the mud sample in the chamber.At the end of the 30-minute filtration time, the volume of filtrate is reported as API filtration. inmilliliters. To obtain correlative results, one thickness of the proper 9-cm filter paper—Whatman No. 50, S&S No. 5765, or the equivalent—must be used. Thickness of the filter cake is measured and reported in 32nd of an inch. The cake isvisually examined, and its consistency is reported using such notations as “hard,” “soft,” tough,” ’‘rubbery,” or “firm.”</div><div style="color: black; text-align: justify;"><br />
</div><div style="color: black; text-align: justify;"><b>Sand Content </b>The sand content indrilling fluids is determined using a 200-mesh sand sieve screen 2 inches indiameter, a funnel to fit the screen, and a glass-sand graduated measuring tube (Figure 1.5). The measuring<br />
tube is marked to indicate the volume of “mud to be added,” water to be added and to directly read the volume of sand on the bottom of the tube.Sand content of themud is reported in percent by volume.Also reported is thepoint of sampling (e.g.,flowline, shale shaker, suctionpit). Solids other than sandmay be retained on the screen (e.g., lost circulationmaterial), and the presence of such solids should be noted.</div><div style="color: black; text-align: justify;"><br />
</div><div style="color: black; text-align: justify;">Liquids and Solids Content A mud retort is used to determine the liquids and solids content of a drilling fluid.Mud is placed in a steel container and heated at high temperature until the liquid components have been<br />
distilled off and vaporized (Figure 1.6). The vapors are passed through a condenser and collected in a graduated cylinder. The volume of liquids (water and oil) is then measured. Solids, both suspended and dissolved, are determined by volume as a difference between the mud in container and the distillate in graduated cylinder. Drilling fluid retorts are generally designed to distill 10-, 20-, or 50-ml sample volumes</div><div style="color: black; text-align: justify;"><br />
</div><div style="color: black; text-align: justify;"><br />
</div><div style="color: black;"><br />
</div>mayaisjakahttp://www.blogger.com/profile/11820472336428156095noreply@blogger.com2tag:blogger.com,1999:blog-581689683275924296.post-84393776580604452252010-06-08T20:47:00.000-07:002010-06-08T20:47:58.439-07:00Soil: The Living Matrix<b> Introduction</b><br />
<div style="text-align: justify;">Around the world, farmers are very intelligent and know the characteristics of soil. They know many things about the soil that scientists do not, and scientists know many things that farmers do not, so these two groups of workers must work together. This is true of North American, European, and Asian countries. Farming practices are based on empirical experience; some of these practices may not stand up to scientific testing, but others obviously must do.The importance of soil structure as a factor in soil fertility is becoming increasingly clear. If a plant is to grow, its roots must spread so that their delicate structures of root hairs can get access to plant nutrients. They also only thrive if there is an adequate supply of water and air. In several countries with plantations of sugarcane, the continuous high yields obtained through irrigation and the extensive application of manure and fertilizers have created problems. Chemical analyzes of the soils <br />
from such areas show that common plant nutrients are still present, but that something has happened to the soil that is interfering with its productivity. At first it was thought that the cane itself is deteriorating, but this is not likely, as it propagates vegetatively. Instead, unfavorable conditions for beneficial soil microorganisms may have been produced. The deterioration of the soil structure seems to play a direct part in this, because soil microorganisms have an important influence on the soil structure. Soil organic matter – the formation, decomposition, and transformation of which are caused by microorganisms – is of great importance to sustainable soilfertility and soil structure.</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;">More experiments on soil structure and other physical properties of soils, such as permeability, porosity, and moisture retention capacity, are desirable. Soil fertility depends on a large number of complex factors, not all of which are known. Physical properties of the soil are no less important than chemical properties. The clay fraction determines many physical and chemical properties of soils. The properties of clays are determined by their mineralogical compositions. X-ray studies and differential thermal analyses of clays have now become necessities in soil laboratories. The electrochemical properties of clays are fundamentally important to understanding soil behavior. This chapter introduces the various types of soil and their functions, as well as the pollution of the soil with heavy metals, which is detrimental to the health of the soil</div><div style="text-align: justify;"><br />
</div><div style="text-align: center;"><b>Soil Taxonomy and Classification</b></div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;">A soil taxonomist distinguishes soils partly on the basis of the kind of diagnostic horizon(s) present in each soil. The current soil taxonomy (classification) was adopted in 1965; a simplified account of this classification system follows below(see US Soil Survey Report 1972, 1975). Order. This is the most general category. All soils fit into one of ten orders. Suborder. Suborders within a soil order are differentiated largely on the basis of soil properties and horizons resulting from differences in soil moisture and soil temperature. Forty-seven suborders are presently recognized.<br />
</div><div style="text-align: justify;">Great group. Soil great groups are subdivisions of suborders. The 185 great groups found in the US, and 225 worldwide, have been established largely on the basis of differentiating soil horizons and soil features. The soil horizons include those that have accumulated clay, iron, and/or humus, and those that have pans <br />
(hardened or cemented soil layers) that interfere with water movement or root penetration.<br />
</div><div style="text-align: justify;">Subgroup. Each soil great group is divided into three kinds of subgroups: one representing the central (typic) segment of the soil group; a second that has prop-erties that tend toward other orders, suborders, or other great groups (intergrade group); and a third that has properties that prevent its classification as typic or intergrade. About 970 subgroups are known in the United States.Family. Subgroups contain soil families, which are distinguished primarily on the basis of soil properties important to the growth of plants or the behavior of soils when used for engineering purposes. These soil properties used include texture, mineral reactions (pH), soil temperature, precipitation pattern of the area, permeability, horizon thickness, structure, and consistency. About 4,500 families have been identified in the United States.Series. Each family contains several (similar) soil series. The 10,500 or more soil series in the United States have narrower ranges of characteristics than a soil family. The name of the soil series has no pedogenic (i.e., related to soil formation) significance; instead, it represents a prominent geographic name of a river, town,or area near where the series was first recognized. Soil series are differentiated on the basis of observable and mappable soil characteristics, such as color, texture, structure, consistency, thickness, reactions (pH), and the number and arrangement of horizons in the soil pedon as well as their chemical and <br />
mineralization properties. Terms describing surface soil texture, percentage slope, stoniness, saltiness, erosion, and other conditions are called phases. Mapping units are created by adding phase names to series names. All mappingunits are polypedons. Prior to 1971, soil type was a mapping unit that was used <br />
to denote a subdivision of a series indicating the series name and surface texture. Soil type is no longer official nomenclature; it has been replaced by series phase.</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;">The prime land means the best land. The definition of prime land will change depending on the use of the land, and full agreement as to exactly how “prime” should be defined is unlikely, even for a specific land use. For farmland use, it is proposed that prime land should meet all the followingrequirements: adequate natu-ral rainfall or adequate and good-quality irrigation water for intended use; mean annual temperature >32°F (0°C) and mean summer temperature >46°F (8°C); lack of excessive moisture – flooding should not occur more often than once every two years; water table should be below the rooting zone; soil should not be excessively acidic, alkaline, or saline; soil permeability should be at least 0.38″ h−1 (1.0 cm h−1) in the upper 20″ (51 cm); the amount of gravel, cobbles, or stones should not be excessive enough to seriously interfere with power machinery; any restricting layer in the soil should be deep enough to permit adequate moisture storage and unhampered root growth, and; the soil should not be excessively erodible.The objectives of soil surveys and taxonomy are to facilitate growth on soils that have never been grown on before, and to learn enough about certain soils to predict how they would respond when irrigated with a specific quantity of irrigation water of known quality. This objective also emphasizes the inclusion of a rational means of transferring technology from one soil to another, interpretations that allow the predition of land use for every soil mapped, and that the survey should serve as a scientific database. Soil surveying has developed into a specialized subject. A survey report contains information on not only the characteristics of the soil and its profile, but also the existing and potential uses of the land, the yields obtained by the farmer or by experimental stations under different systems of management, erosion and drainage conditions, and the potential for reclamation or its suitability for irrigation, where these are necessary. Soil maps and survey reports form the basis for planning the utilization of the land, and they have also been found useful in road and building projects.</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"><br />
</div>mayaisjakahttp://www.blogger.com/profile/11820472336428156095noreply@blogger.com2tag:blogger.com,1999:blog-581689683275924296.post-38046732184777702032010-01-14T22:34:00.000-08:002010-06-01T21:30:33.733-07:00California Bearing Ratio - CBR - Procedures Manual<b>1. SCOPE</b><br />
Description of Test<br />
This method describes the sampling of the subgrade for California Bearing Ratio (C.B.R.). The resulting information is used for pavement design thickness.<br />
<br />
<b>2. APPARATUS AND MATERIALS</b><br />
Equipment Required<br />
<ol><li>A suitable rig equipped with a 150 mm auger.</li>
<li>Large cotton bags (with tags).</li>
</ol><br />
<b>3. PROCEDURE</b><br />
Test Procedure<br />
<ol><li>Take a 35 kg sample at every third group index sample location, spacing may be increased on projects where the material is found to be very uniform. The district materials engineer or his designate will advise on the spacing of sampling. Extreme care must be taken to ensure the sample is not contaminated with prepared Subgrade material (top 5 - 15 cm). </li>
<li>Take a group index sample and C.B.R. sample from the same hole. </li>
<li>The group index sample is taken first, then enlarge the hole to obtain the C.B.R. sample. </li>
<li>Ensure neither sample is contaminated from loose surface materials.</li>
<li>Record control section, station and offset at which the sample was taken on two tags. </li>
<li>Place one tag inside the bag and attach the other to the outside of the bag. </li>
<li>Keep samples dry while stored in the field and transport to the district lab at earliest opportune time. A special trip is not required.</li>
</ol><br />
<b>4. RESULTS AND CALCULATIONS</b><br />
Reporting Results<br />
Record control section, hole number, stationing and offset for further testing as proctor density is completed in the district lab and the C.B.R. testing is completed at the central lab in Regina.<br />
<br />
<b>5. ADDED INFORMATION</b><br />
General<br />
Refer to diagram in STP 104-5 for sampling procedure.<br />
C.B.R. sampling is required on all subgrade types with the exception of clean sandsmayaisjakahttp://www.blogger.com/profile/11820472336428156095noreply@blogger.com0tag:blogger.com,1999:blog-581689683275924296.post-91064904920621621882010-01-15T01:57:00.000-08:002010-06-01T21:30:13.638-07:00California Bearing Ratio C.B.R<div class="separator" style="clear: both; text-align: center;"><br />
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</div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg4B9Go5cTc4j_TVo4UmyA-xSdxkeX5GUhnXKHlcBLK7sz9jEVuq6eEHDnMkOFVL-FzCB3j4_c0bQWLu9-Qm94TleyqdyPcLMlyRqpoMVBJKNDwTRdxlz9RzySnQLZbJPvrI6H5n8AGAw9F/s1600-h/Untitled-2.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg4B9Go5cTc4j_TVo4UmyA-xSdxkeX5GUhnXKHlcBLK7sz9jEVuq6eEHDnMkOFVL-FzCB3j4_c0bQWLu9-Qm94TleyqdyPcLMlyRqpoMVBJKNDwTRdxlz9RzySnQLZbJPvrI6H5n8AGAw9F/s320/Untitled-2.jpg" /></a></div><div style="text-align: center;"><br />
<b>California Bearing Ratio C.B.R</b><br />
<br />
</div>The <b>California Bearing Ratio (CBR)</b> test is a simple strength test that compares the bearing capacity of a material with that of a well-graded crushed stone (thus, a high quality crushed stone material should have a CBR <span style="font-family: Symbol; font-size: x-small;">@</span> 100%). It is primarily intended for, but not limited to, evaluating the strength of cohesive materials having maximum particle sizes less than 19 mm (0.75 in.) <b>(AASHTO, 2000)</b>. It was developed by the California Division of Highways around 1930 and was subsequently adopted by numerous states, counties, U.S. federal agencies and internationally. As a result, most agency and commercial geotechnical laboratories in the U.S. are equipped to perform CBR tests.<br />
<br />
The basic CBR test involves applying load to a small penetration piston at a rate of 1.3 mm (0.05") per minute and recording the total load at penetrations ranging from 0.64 mm (0.025 in.) up to 7.62 mm (0.300 in.). Figure Below is a sketch of a typical CBR sample.<br />
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEikYPT_Ul553NrfU0rwlqlyRaWA7urOKPTxTyIorSkZG5ewQ_sZbfKij7t-uP-VVFpJAnP5bnxuJzjHBlXJq98SknWTvDLXsVlH0-qdw1VHydkSzXiYu1-W7TgE0UCZonokPwk1K8MSLlVd/s1600-h/cbr.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEikYPT_Ul553NrfU0rwlqlyRaWA7urOKPTxTyIorSkZG5ewQ_sZbfKij7t-uP-VVFpJAnP5bnxuJzjHBlXJq98SknWTvDLXsVlH0-qdw1VHydkSzXiYu1-W7TgE0UCZonokPwk1K8MSLlVd/s320/cbr.jpg" /></a></div><div style="text-align: center;"><b>CBR Sample</b></div><div style="text-align: left;"><br />
</div>Values obtained are inserted into the following equation to obtain a CBR value:<br />
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgwE4Xfg8W6yvX4je4_HHhAUAmNUNx4oH4K1HBwRnX7gB1hqXsVlNBvvhWULsDmC2wzDByDiOS2u-UiPbNei-_b6K8LyvwVhVE5CrGbZ1L8gC1dU1UCzqnP34QxIX9G4qj6kDJ3ItnX9543/s1600-h/image002.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgwE4Xfg8W6yvX4je4_HHhAUAmNUNx4oH4K1HBwRnX7gB1hqXsVlNBvvhWULsDmC2wzDByDiOS2u-UiPbNei-_b6K8LyvwVhVE5CrGbZ1L8gC1dU1UCzqnP34QxIX9G4qj6kDJ3ItnX9543/s320/image002.gif" /></a></div><div class="separator" style="clear: both; text-align: left;"><br />
</div><table border="0" bordercolor="#111111" cellpadding="7" cellspacing="0" height="156" style="border-collapse: collapse; width: 533px;"><tbody>
<tr><td height="31" style="text-align: center;" valign="TOP" width="46">where:</td> <td height="31" valign="TOP" width="9">x</td> <td height="31" valign="TOP" width="9">=</td> <td height="31" style="text-align: left;" valign="TOP" width="413">material resistance or the unit load on the piston (pressure)<br />
for 2.54 mm (0.1") or 5.08 mm (0.2") of penetration</td> </tr>
<tr><td height="28" valign="TOP" width="46"><br />
</td> <td height="28" valign="TOP" width="9">y</td> <td height="28" valign="TOP" width="9">=</td> <td height="28" style="text-align: left;" valign="TOP" width="413">standard unit load (pressure) for well graded crushed stone</td> </tr>
<tr><td height="28" valign="TOP" width="46"><br />
</td> <td height="28" valign="TOP" width="9"><br />
</td> <td height="28" valign="TOP" width="9">=</td> <td height="28" style="text-align: left;" valign="TOP" width="413">for 2.54 mm (0.1") penetration = 6.9 MPa (1000 psi)</td> </tr>
<tr><td height="28" valign="TOP" width="46"><br />
</td> <td height="28" valign="TOP" width="9"><br />
</td> <td height="28" valign="TOP" width="9">=</td> <td height="28" style="text-align: left;" valign="TOP" width="413">for 5.08 mm (0.2") penetration = 10.3 MPa (1500 psi)</td></tr>
</tbody></table><div class="separator" style="clear: both; text-align: left;"><br />
</div><div class="separator" style="clear: both; text-align: left;">Table below shows some typical CBR ranges.</div><div class="separator" style="clear: both; text-align: left;"><br />
</div><div class="separator" style="clear: both; text-align: left;"><br />
</div><div style="text-align: left;"><b>Typical CBR Ranges</b></div><div style="text-align: left;"><br />
</div><div class="caption">Typical CBR Ranges</div><table border="1" bordercolor="#111111" cellpadding="0" cellspacing="0" height="305" style="border-collapse: collapse; width: 426px;"><tbody>
<tr><td bgcolor="#e6e6e6" height="27" width="148"><b>General Soil Type</b></td> <td bgcolor="#e6e6e6" height="27" width="144"><div align="CENTER"><b>USC Soil Type</b></div></td> <td bgcolor="#e6e6e6" height="27" width="130"><div align="CENTER"><b>CBR Range</b></div></td> </tr>
<tr><td height="161" rowspan="8" width="148">Coarse-grained soils</td> <td height="21" valign="TOP" width="144"><div align="CENTER">GW</div></td> <td height="21" valign="TOP" width="130"><div align="CENTER">40 - 80</div></td> </tr>
<tr> <td height="21" valign="TOP" width="144"><div align="CENTER">GP</div></td> <td height="21" valign="TOP" width="130"><div align="CENTER">30 - 60</div></td> </tr>
<tr> <td height="21" valign="TOP" width="144"><div align="CENTER">GM</div></td> <td height="21" valign="TOP" width="130"><div align="CENTER">20 - 60</div></td> </tr>
<tr> <td height="21" valign="TOP" width="144"><div align="CENTER">GC</div></td> <td height="21" valign="TOP" width="130"><div align="CENTER">20 - 40</div></td> </tr>
<tr> <td height="21" valign="TOP" width="144"><div align="CENTER">SW</div></td> <td height="21" valign="TOP" width="130"><div align="CENTER">20 - 40</div></td> </tr>
<tr> <td height="21" valign="TOP" width="144"><div align="CENTER">SP</div></td> <td height="21" valign="TOP" width="130"><div align="CENTER">10 - 40</div></td> </tr>
<tr> <td height="21" valign="TOP" width="144"><div align="CENTER">SM</div></td> <td height="21" valign="TOP" width="130"><div align="CENTER">10 - 40</div></td> </tr>
<tr> <td height="21" valign="TOP" width="144"><div align="CENTER">SC</div></td> <td height="21" valign="TOP" width="130"><div align="CENTER">5 - 20</div></td> </tr>
<tr><td height="121" rowspan="6" width="148">Fine-grained soils</td> <td height="21" valign="TOP" width="144"><div align="CENTER">ML</div></td> <td height="21" valign="TOP" width="130"><div align="CENTER">15 or less</div></td> </tr>
<tr> <td height="21" valign="TOP" width="144"><div align="CENTER">CL LL < 50%</div></td> <td height="21" valign="TOP" width="130"><div align="CENTER">15 or less</div></td> </tr>
<tr> <td height="21" valign="TOP" width="144"><div align="CENTER">OL</div></td> <td height="21" valign="TOP" width="130"><div align="CENTER">5 or less</div></td> </tr>
<tr> <td height="21" valign="TOP" width="144"><div align="CENTER">MH</div></td> <td height="21" valign="TOP" width="130"><div align="CENTER">10 or less</div></td> </tr>
<tr> <td height="21" valign="TOP" width="144"><div align="CENTER">CH LL > 50%</div></td> <td height="21" valign="TOP" width="130"><div align="CENTER">15 or less</div></td> </tr>
<tr> <td height="21" valign="TOP" width="144"><div align="CENTER">OH</div></td> <td height="21" valign="TOP" width="130"><div align="CENTER">5 or less</div></td></tr>
</tbody></table><div class="separator" style="clear: both; text-align: center;"><br />
</div>Standard CBR test methods are:<br />
<b>AASHTO T 193</b>: The California Bearing Ratio<br />
<div style="text-align: left;"><b>ASTM D 1883</b>: Bearing Ratio of Laboratory Compacted Soils</div><div style="text-align: right;"><span style="font-size: x-small;">Source : training.ce.washington.edu</span> </div><div style="text-align: left;"><br />
Other source : <br />
<br />
The <b>California bearing ratio</b> (<b>CBR</b>) is a penetration test for evaluation of the mechanical strength of road subgrades and basecourses. It was developed by the California Department of Transportation.<br />
The test is performed by measuring the pressure required to penetrate a soil sample with a plunger of standard area. The measured pressure is then divided by the pressure required to achieve an equal penetration on a standard crushed rock material. The CBR test is described in ASTM Standards D1883-05 (for laboratory-prepared samples) and D4429 (for soils in place in field), and AASHTO T193.<br />
The CBR rating was developed for measuring the load-bearing capacity of soils used for building roads. The CBR can also be used for measuring the load-bearing capacity of unimproved airstrips or for soils under paved airstrips. The harder the surface, the higher the CBR rating. A CBR of 3 equates to tilled farmland, a CBR of 4.75 equates to turf or moist clay, while moist sand may have a CBR of 10. High quality crushed rock has a CBR over 80. The standard material for this test is crushed California limestone which has a value of 100.<br />
<br />
<img alt="CBR=\frac {p}{p_s} \cdot 100 \quad " class="tex" src="http://upload.wikimedia.org/math/b/9/e/b9e6ba71a61f929e3ec5969af097ffa5.png" /><br />
<br />
<table><tbody>
<tr> <td><img alt="CBR \quad" class="tex" src="http://upload.wikimedia.org/math/3/0/a/30a9d7aa726ea06dbf5c7af7d3dda6b7.png" /></td> <td>= CBR [%]</td> </tr>
<tr> <td><img alt="p \quad" class="tex" src="http://upload.wikimedia.org/math/a/8/e/a8e6935e3a7e158bf1a50874718e93cd.png" /></td> <td>= measured pressure for site soils [N/mm²]</td> </tr>
<tr> <td><img alt="p_s \quad" class="tex" src="http://upload.wikimedia.org/math/c/3/2/c3216b915eb5b22d1d6fd8e3a52f8f46.png" /></td> <td>= pressure to achieve equal penetration on standard soil [N/mm²]</td></tr>
</tbody></table></div><div style="text-align: left;"><br />
<div style="text-align: right;"><b><span style="font-size: x-small;"> source : wikipedia</span><br />
</b></div><br />
<b>CBR Component</b> :</div><span id="goog_1263549479781"></span><span id="goog_1263549479782"></span><br />
<div class="separator" style="clear: both; text-align: center;"><br />
</div><ol><li><b>Swell Plate</b> : Contact end of the stem is easily locked in place with a knurled nut. </li>
<li><b>Swell Tripod Attachment</b> : Metal tripod supports dial gauge for measuring the amount of swell during soaking. Attachment is used with swell plate. Order dial indicator separately. <br />
</li>
<li><b>Dial Indicator</b> : Dial indicator has 1.000" operating range, graduated in 0.001" divisions, clockwise movement and revolution counter.</li>
<li><b>Cutting Edge</b> : Machined from seamless tubing with a sharpened edge to enable undisturbed samples to be taken in the field, cutting edge is plated for rust resistance. Cutting edge has 6" (152mm) ID and is 2" (51mm) high. Recess in upper section allows edge to be mounted at either end of the Compaction Mold or CBR Mold with Perforated Base mold to facilitate sample removal in the field.</li>
<li><b>Filter Screen</b> :</li>
<li><b>Filter Paper : </b>used to separate spacer disc and soil in the CBR mold during compaction operation or over the top surface of the soil when the compaction operation is completed.</li>
<li><b>Surcharge Weigh</b>t : Used in the application of surcharged loads on the soil‘s surface during soaking and penetration. Rust-resistant, plated annular disc weighs 5 lbs. (2.3kg), 5-7/8" (149mm) OD with a 2-1/8" (54mm) ID hole in center.</li>
<li><b>Slotted Surcharge Weight</b> </li>
<li><b>Spacer Disc</b> : Disc is used as a false bottom in a soil mold during the compaction process.</li>
<li><b>Penetration Piston</b> : CBR Penetration Piston has 3 sq. in. (19.35cm<sup>2</sup>) base area and is about 7-1/2" (191mm) long. Designed for use in conjunction with weights <b>Surcharge Weight </b> and <b>Slotted Surcharge Weight</b> to apply penetration surcharge loads.</li>
<li><b>Dial Indicator Bracket</b> : Bracket used to attach a dial indicator to the penetration piston.</li>
<li><b>Swivel Base</b> : for mechanical jack <br />
</li>
</ol><div style="text-align: right;"><span style="font-size: x-small;"> source : humbolt</span><br />
<div style="text-align: left;"><br />
</div><div style="text-align: left;"><span style="font-size: x-small;"><span style="font-size: small;"><b>TYPE OF CALIFORNIA BEARING RATIO </b></span></span></div><div style="text-align: left;"><br />
</div><div style="text-align: left;"><span style="font-size: x-small;"><span style="font-size: small;"><b>1. </b></span><br />
</span></div></div><div style="text-align: right;"><span style="background-color: black;"></span></div><div style="text-align: right;"><span style="background-color: orange;"></span><br />
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</div>mayaisjakahttp://www.blogger.com/profile/11820472336428156095noreply@blogger.com4tag:blogger.com,1999:blog-581689683275924296.post-73914212170233625402010-01-17T13:03:00.000-08:002010-06-01T21:29:42.382-07:00Cone Penetration Test<div style="font-family: inherit;"><span style="font-size: small;"><b>Description</b></span></div><div style="font-family: inherit;"><span style="font-size: small;"><br />
</span></div><div style="font-family: inherit;"><span style="font-size: small;"><b>Cone Penetrometer Technology</b> (CPT) is a method of providing real-time data for use in characterizing the subsurface, as opposed to older methods of analyzing subsurface conditions in the laboratory. It consists of a steel cone that is hydraulically pushed into the ground at up to 40,000 pounds of pressure. Sensors on the tip of the cone collect data. Standard cone penetrometers collect information to classify soil type by using sensors that measure cone-tip pressure and friction. CPT is often used in conjunction with Hydropunch tests, which use the CPT holes to extract groundwater for laboratory analysis. An innovation of the CPT (i.e., the wireline CPT) allows multiple CPT tools to be interchanged during a single penetration, without withdrawing the CPT rod string from the ground.</span></div><div style="font-family: inherit;"><span style="font-size: small;"><br />
</span></div><div style="font-family: inherit;"><span style="font-size: small;">Initially developed to collect information about soil characteristics, as sensor technology was developed CPT also became a platform for collecting information about a variety of contaminants. Recent advances in sensor technology have expanded cone penetrometer capabilities to detect the presence of petroleum hydrocarbons. Sensors are being tested or demonstrated for the detection of other organics, compounds, metals, radioactivity, explosives, and soil moisture.</span></div><div style="font-family: inherit;"><span style="font-size: small;"><br />
</span></div><div style="font-family: inherit;"><span style="font-size: small;"><b> Cone penetration testing (CPT)</b> is the most versatile device for in situ soil testing. Without disturbing the ground, it provides information about soil type, geotechnical parameters like shear strength, density, elastic modulus, rates of consolidation and environmental properties. Further, as it can be seen as a small scale test pile, it is the best and most cost-effective device to design piled foundations and sheet piles.</span></div><div style="font-family: inherit;"><span style="font-size: small;"><br />
</span></div><div style="font-family: inherit;"><span style="font-size: small;"><br />
</span></div><div style="font-family: inherit;"><span style="font-size: small;"><b>Limitations and Concerns</b></span></div><div style="font-family: inherit;"><span style="font-size: small;"><br />
</span></div><div style="font-family: inherit;"><span style="font-size: small;"><b>CPT</b> cannot be used at some sites due to high soil density. Most sensors are now used as screening tools that provide initial site characterization data. The data is confirmed by collecting samples that are analyzed in the laboratory. This is due to limitations in sensor technology, and it will likely diminish in importance as the technology improves.</span></div><div style="font-family: inherit;"><span style="font-size: small;"><br />
</span></div><div style="font-family: inherit;"><span style="font-size: small;"><b>CPT</b> is useful on sites that contain unconsolidated sediments (e.g., soil and clay that are not cemented together). On the other hand, sites with large boulders, rock or cemented layers are difficult to penetrate. </span></div><div style="font-family: inherit;"><span style="font-size: small;">CPT sensors, such as lasers, that require a lens may be hampered by fouling of the lens due to a reaction to dust. Decontamination may be necessary if the CPT comes into contact with contaminated material.</span></div><div style="font-family: inherit;"><span style="font-size: small;"><br />
</span></div><div style="font-family: inherit;"><span style="font-size: small;"><br />
</span></div><div align="left" style="font-family: inherit;"><span style="font-size: small;">Cone Penetration Tests are conducted to obtain the cone resistance, the side friction and, if there is a piezocone, the pore pressure. The soil type can be determined by analysing these results, the values can also be used in the design of shallow foundations through the estimation of stiffness and shear strength of cohesive soils.</span></div><div align="left" style="font-family: inherit;"><span style="font-size: small;">A 60<sup>o</sup> cone with face area 10cm</span><span style="font-size: small;"><sup>2</sup></span><span style="font-size: small;"> and 150cm</span><span style="font-size: small;"><sup>2</sup></span><span style="font-size: small;"> 'friction sleeve' is hydraulically pushed into the ground at a constant speed (ranging form 1.5 to 2.5 cm/s). The force required to maintain this penetration rate, and the shear force acting on the friction sleeve are recorded. The friction ratio (cone resistance / side friction) gives an indication of the soil type. </span></div><blockquote style="font-family: inherit;"><blockquote><div align="left"><span style="font-size: small;"><b>Cone Resistance q<sub>c</sub> = F<sub>c</sub> / A<sub>c</sub></b></span></div><div align="left"><span style="font-size: small;"><b>Side Friction f<sub>s</sub> = F<sub>s</sub> / A<sub>s</sub></b></span></div><div align="left"><span style="font-size: small;"><b>Friction Ratio R<sub>f</sub> = f<sub>s</sub> / q<sub>c</sub></b></span></div></blockquote></blockquote><div align="left" style="font-family: inherit;"><span style="font-size: small;">Where F<sub>c</sub> = pushing force, A<sub>c</sub> = cone plan area, F<sub>s</sub> = shear force on friction sleeve, A<sub>s</sub> = area of friction sleeve. </span></div><div style="font-family: inherit;"><span style="font-size: small;"><br />
</span></div><div style="font-family: inherit;"><span style="font-size: small;"><br />
</span></div><div style="font-family: inherit;"><span style="font-size: small;"> source : civcal.media.hku.hk, www.conepenetration.com, www.cpeo.org</span></div>mayaisjakahttp://www.blogger.com/profile/11820472336428156095noreply@blogger.com1tag:blogger.com,1999:blog-581689683275924296.post-36754042297588540362010-01-17T18:07:00.000-08:002010-06-01T21:28:00.589-07:00Electric Cone Penetration Test (CPT)<b>Cone penetration tests (CPT) </b><br />
<br />
An <b>Electric Cone Penetration Test (CPT)</b> is a geomechanical probing technique for shallow subsurface exploration. Probing through weak ground to locate firmer strata at depth has been practised since 1917, but CPT developed into its final form in the Netherlands during the 1930’s (Lunne et al. 1997). CPT combines rapid and cheap insight in the mechanical composition of the subsurface in the upper tens of meters. The widest application is currently found in geomechanical applications, i.e. surveys for road and railway constructions and the foundation of buildings and houses in areas with weak subsurface. The principles of <b>CPT</b> are published in Lunne et al. (1997) and Coerts (1996).<br />
<br />
<b>Principles of cone penetration tests</b><br />
<br />
<i><b>Cone resistance, sleeve friction and friction ratio</b></i><br />
<b>CPT</b> surveying involves the penetration of a metal electrical cone with a surface of 10 cm2 into the subsurface (Fig. 4.9.1). From beneath a heavy truck, the cone is penetrated at a constant rate of 1 cm/s. During penetration, a number of variables are recorded at the cone head or along the sleeve. At the cone head the cone resistance (qc) is recorded (in MPa), which expresses the resistance of the sediments to penetration. Along the cone the sleeve friction (fs) is recorded (also in MPa); indicative for the adhesive strength of the material.<br />
<br />
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjQn7E8me19AehggY4H9-qw1CeCOR4O3uGjvp6ef5Wjntzqvqmj8uIqdHBIY-lGOJK6X_QW6Cb7-0MZYPMAeCsvJ97zWxuClRbLJ6EAMmr0BaUYtKnKYao7crkVnk_g21lAkqoILUBmzlUW/s1600-h/Untitled-1.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjQn7E8me19AehggY4H9-qw1CeCOR4O3uGjvp6ef5Wjntzqvqmj8uIqdHBIY-lGOJK6X_QW6Cb7-0MZYPMAeCsvJ97zWxuClRbLJ6EAMmr0BaUYtKnKYao7crkVnk_g21lAkqoILUBmzlUW/s320/Untitled-1.jpg" /></a></div><div class="separator" style="clear: both; text-align: center;">Terminology for cone penetrometers </div>(from Lunne et al. 1997).<br />
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</div><div class="separator" style="clear: both; text-align: left;">From the cone resistance and the sleeve friction the friction ratio (Rf) can be calculated according: </div><br />
<div style="text-align: center;"><b>Rf = [(fs /qc)*100] <br />
</b></div><div class="separator" style="clear: both; text-align: left;"><br />
</div>Numerous analyses of data have lead to an empirical relationship between Rf and inferred lithology (Table Below). The friction ratio is, in combination with cone resistance, broadly used in geomechanical applications. <br />
<br />
<div style="text-align: center;">Empirical relation between the dimensionless friction ratio and inferred lithology in CPT.</div><div style="text-align: center;"><br />
</div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiRjCAfYQsvf3rJta1CSk3SrqM9deLj3x8lmUbp8RYmeqMVyaC1tqz9pHIE9FxxfPa06PXuJGFb8Usn8Grad7iCcLq3Q9TJlOokatM4BRTIAjE4HG3Jt1gxcnPsMI-AU_M9HOmisE_qhAYa/s1600-h/Untitled-2.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiRjCAfYQsvf3rJta1CSk3SrqM9deLj3x8lmUbp8RYmeqMVyaC1tqz9pHIE9FxxfPa06PXuJGFb8Usn8Grad7iCcLq3Q9TJlOokatM4BRTIAjE4HG3Jt1gxcnPsMI-AU_M9HOmisE_qhAYa/s320/Untitled-2.jpg" /></a></div><div class="separator" style="clear: both; text-align: left;"><br />
</div><div class="separator" style="clear: both; text-align: left;"><b>Pore water pressure </b></div><div class="separator" style="clear: both; text-align: left;"><br />
</div><div class="separator" style="clear: both; text-align: left;">Another useful parameter that can be recorded in <b>CPTU</b> surveying (the so-called piezocone test) is </div>the pore pressure u (Fig. 4.9.1). In the saturated or vadose zone increasing values occur with increasing depth, expressed in MPa. Also perched ground water tables can be detected using this technique. <br />
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</div><div class="separator" style="clear: both; text-align: left;"><b>Data interpretation</b></div><div class="separator" style="clear: both; text-align: left;"><br />
</div><div class="separator" style="clear: both; text-align: left;"><b>CPT </b>interpretation mainly involves pattern analysis of the cone resistance and friction ratio </div>curves. In common practice it is possible to define CPT „facies“ for certain sedimentary deposits. In buried valley environments for example, the friction ratio curve characteristics of “pot clay“ (or Lauenburger Ton) are well known. Similar typical CPT facies units can be defined for cover sands, boulder clay (till), several fluvial deposits and so forth. Figure 4.9.2 demonstrates an example of a CPT plot in which typical “pot clay“ <br />
patterns can be recognized between 22 and 29 m depth. Less distinct are the clayey deposits between 0 and 22 m depth. <br />
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</div><div style="text-align: center;"></div><div style="text-align: center;"></div><div style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi4T31cqnKHmou34i2-n_g-CcMUGEZei4quSA62hi7U9pxKqefECLtWfEIukXxRZdGkNebUJ8FwR2aS3D_ASghG7voykinKKcWDkp4wzy1Np5UCRoGUE7S5lnyXiuBXgafKzymNVE71zr8c/s1600-h/Untitled-3.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi4T31cqnKHmou34i2-n_g-CcMUGEZei4quSA62hi7U9pxKqefECLtWfEIukXxRZdGkNebUJ8FwR2aS3D_ASghG7voykinKKcWDkp4wzy1Np5UCRoGUE7S5lnyXiuBXgafKzymNVE71zr8c/s400/Untitled-3.jpg" /></a></div><div style="text-align: center;"><b>Fig 2</b></div><div style="text-align: center;"><br />
</div><div style="text-align: center;"> Fig.2 - CPT log showing sedimentary units associated to buried valley infill, including “pot clay“ deposits (PENI). PE=Peelo Formation; PENI = Nieuwolda Member of the Peelo Formation, BX = Boxtel Formation (Weichselian deposits).</div><br />
Ideally, site-specific CPT „facies“ have to be verified with borehole data or observations from exposures to ascertain relationships with actual lithofacies units. <b><br />
</b><br />
<br />
<b>Application of CPT in the study of buried valleys</b><br />
<br />
<b>CPT</b> is a useful, fast and cost-effective technique that can be used for the following applications related to the characterisation of buried valleys; <br />
1. the establishment of the occurrence, extenand upper boundary of “pot clay“ bodies <br />
2. the establishment of protecting impermeable beds above buried valley aquifer systems (such as “pot clay“, boulder clay, etc.) <br />
3. characterisation of the upper sedimentary records outside buried valleys. <br />
<br />
Figure 5.6.8 presents a <b>CPT transect</b>, combined with lithological columns of boreholes, of the <br />
Groningen Burval project area. Particularly between 2 and 4 km along the profile, a large clayey body is identified. The presence and rough outline of this unit was also demonstrated by Helicopter Electromagnetics . Below this unit other sediments associated with the Peelo Formation occur, while near the surface Weichselian deposits are present (Boxtel Formation). Figure 4.9.3 shows an enlarged part of Figure 5.6.8 to demonstrate the correlation more clearly. <br />
<br />
The CPT characteristics of the “pot clay“ (PENI) are clearly defined. The deeper undifferentiated deposits of the Peelo Formations are characterised by a strong lateral and vertical heterogeneity. <br />
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</div><div style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi-U_oekbFkisMRDD2tI4MO66c4fCGtRH0xn_hSYRSw0j3OIF0C4eTAP522virFNDPv0TxJvPEzoKDbsen3iJ8YnnIyaHQkzBa64-a03mT7uNRtqUOHNLJPgRo9in0C8HfGWTWSBg20dRoG/s1600-h/Untitled-4.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi-U_oekbFkisMRDD2tI4MO66c4fCGtRH0xn_hSYRSw0j3OIF0C4eTAP522virFNDPv0TxJvPEzoKDbsen3iJ8YnnIyaHQkzBa64-a03mT7uNRtqUOHNLJPgRo9in0C8HfGWTWSBg20dRoG/s400/Untitled-4.jpg" /></a></div><div class="separator" style="clear: both; text-align: center;"><br />
</div><br />
<div style="text-align: center;">Fig. 4.9.3: Enlarged part of Figure 5.6.8. <b>CPT</b> transect with lithological columns of boreholes across unit of low-resistivity in HEM data. PE=Peelo Formation; PENI=Nieuwolda Member of the Peelo Formation, consisting of “pot clay“. BX =Boxtel Formation (Weichselian deposits).</div><div style="text-align: center;"><br />
</div><div style="text-align: left;"><b>Some remarks on the application of CPT </b></div><div style="text-align: left;"><br />
</div><div style="text-align: left;"><b>CPT</b> can be broadly used in unconsolidated sediments; however there are certain limitations that have to be kept in mind:</div><div style="text-align: left;"><br />
</div><ol><li>The empirical relationship presented in Table 4.9.1 is based on observations below the ground water table. Above the ground water table a clayey bed (for example) can be partly dried out, leading to higher cone resistance and lower sleeve friction, hence lowering the friction ratio number. However in a climate with excess rainfall like that in northwestern Europe, hanging water is likely in the unsaturated zone. Hence it should be possible to discriminate clayey beds from their sand or gravely counterparts in the unsaturated zone. <br />
</li>
<li>In buried valley environments glaciotectonized sediments can occur. The same is true for overconsolidated sediments due to glacial loading. In both situations geomechanical properties of the sedimentary record is potentially modified: sediments could respond different to CPT than expected in in situ sedimentary sequences following the stratigraphical rule (Bakker 2004). In situations with overconsolidated clay adhesive strength is relatively high, but possibly reduced due to mechanical expel of pore water. Cone resistance is enhanced (higher compaction), leading to a reduced Rf. Hence, Rf values can differ from normal sedimentaryconditions, with normal setting and compaction due to overburden.</li>
</ol>The examples demonstrated above, attest that CPT is a powerful technique for the identification and mapping of large sedimentary units to a maximum depth of about 60 m below the surface. Combined with the low-costs CPT is a technique that is highly recommendable in environments with unconsolidated sediments such as buried valley systems. <br />
<br />
<b>References </b>:<br />
<br />
<ol><li>Bakker MAJ (2004): The internal structure of Pleistocene push moraines. A multidisciplinary approach with emphasis on ground- penetrating radar. – PhD thesis, Queen Mary, University of London, 177 pp.</li>
<li>Coerts A (1996): Analysis of static cone penetration test data for subsurface modelling. A methodology. – PhD thesis, Netherlands Geographical Studies 210, 263 pp.</li>
<li>Lunne T, Robertson PK, Powell JJM (1997): Cone Penetration Testing in Geotechnical Practice. – Blackie Academic & Professional, London, 312 pp. <br />
</li>
</ol><div style="text-align: right;"><span style="font-size: x-small;">Source : Burval</span></div><div style="text-align: left;"><br />
</div>mayaisjakahttp://www.blogger.com/profile/11820472336428156095noreply@blogger.com1tag:blogger.com,1999:blog-581689683275924296.post-60104763982285223142010-01-19T21:07:00.000-08:002010-06-01T21:27:05.752-07:00Selecting and Using a Soil Testing Laboratory<b>Taking a Soil Sample</b><br />
<br />
<div style="text-align: justify;">Follow the specifc instructions provided by the soil testing lab you select. The following guidelines will help ensure that a good sample is taken: Separate samples should be taken for distinct areas- front yard, back yard, vegetable garden, etc. The sample should represent the soil in which the plants are or will be growing. Use a spade or trowel to take 10-12 random samples across the area of concern. The samples are thin slices taken to a depth that contains or will contain the bulk of the plant’s roots- 3 inches for turf; 6-8 inches for garden and landscape beds. Mix together all of the slices in a clean bucket removing all rocks, debris, and <br />
plant material.</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"><b>Mailing in a Soil Sample</b></div><div style="text-align: justify;"><br />
Don’t send wet soil; you should not be able to squeeze water from the sample. Send a minimum of 1 cup and a maximum of 2 cups of soil per sample. If no kit is provided, seal the soil in a zip lock bag or use the special soil sample bag provided by the Maryland Department of Agriculture and Maryland Cooperative Extension. Forms for most of the labs can be downloaded from their websites. Be sure that all of your contact information is on the form and mail it back to the lab with the sample, check for the correct amount, and suffcient postage</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"><b>Interpreting Test Results</b></div><div style="text-align: justify;"><br />
Soil test reports from all of the labs will provide a graphical representation of results- the level of various nutrients from your soil (low medium, high, excessive). “Optimal” and “excessive” levels mean that the nutrient concentration in the soil is more than adequate for optimum plant growth. Adding more of that nutrient will not improve plant growth and may have undesirable effects on the environment.<br />
<br />
</div><div style="text-align: justify;">Be aware that the specifc turfgrass fertilizer recommendations you receive will not be identical to Maryland’s. This is due to differences in soils, climate, and and state water quality policies. Always follow University of Maryland recommendations for applying the right amount of nitrogen for healthy lawns. Go to the “Publications” section of our website to download the following fact sheets: HG 103, “Fertilizing Facts for <br />
Home Lawns”; FS 702, “Lawns and the Chesapeake Bay” (has more detailed information on grasscycling, slow release nitrogen fertilizers, and fertilizing responsibly); and HG 42, “Soil Amendments and Fertilizers” (contains broad fertilizer guidelines for many garden and landscape plants).</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"><b>Abbreviations and Terms Found in Soil Test </b><br />
</div><div style="text-align: justify;"><b>Reports</b></div><div style="text-align: justify;"><br />
The labs listed in the chart provide defnitions and explanations of soil sampling terms and concepts. The list below will help you better understand the soil test reports you receive. pH- soil pH is a measure of a soil’s hydrogen ion concentration. The greater the number of hydrogen ions the more acidic the soil. The pH scale is 1-14. </div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;">Soils with pH levels below 7.0 are considered acidic and soils with pH levels above 7.0 are considered alkaline. Soil pH is a critical measurement for gardeners because it affects the availability of nutrients for uptake by plant roots. Most garden and landscape plants grow best in soils with a pH of 5.5–7.0. Certain plant nutrients can become unavailable or excessively available outside this range, leading to plant growth problems. But there are exceptions: for example, plants in the azalea and blueberry family grow best at pH 4.0-5.0.</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"><b>Macronutrients:</b> these are required in the greatest quantity by plants. Sulfur (S) is rarely tested because soils in Maryland are rarely defcient. Nitrogen (N) is not usually tested because it is constantly changing.<br />
<b>P- phosphorous<br />
K- potassium<br />
Mg- magnesium<br />
Ca- calcium</b></div><div style="text-align: justify;"><br />
<b>Micronutrients:</b> These important nutrients are required in relatively small quantities. Defciencies are rarely a problem in Maryland soils, especially in the Central and Western regions. Eastern Shore gardeners may want to be sure that boron is included in the test they select.<br />
<b>Fe- iron<br />
Zn- zinc<br />
Cu- copper<br />
Mn- manganese<br />
B- boron</b></div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"><b>Heavy metals: </b> excessive levels are a concern, especially in soils where food crops are grown and children play. These elements can be a health hazard when 1)tracked into the house via shoes and tools, 2)ingested by young children, or 3)ingested from food crops grown in contaminated soil. For more information on lead, <br />
refer to Maryland Cooperative Extension fact sheet HG #18, ”Lead in Garden Soil.”<br />
<b>Pb- lead<br />
Ni- nickel<br />
Cd- cadmium<br />
Cr- chromium</b></div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;">OM- organic matter; includes living and decomposed plant and animal tissues (dead leaves, soil fungi, plant roots, etc. Soil organic matter drives a soil’s biological and chemical processes. OM test results are given on a weight basis. Usually a sample is weighed in the lab and then ignited to burn off the carbon compounds, leaving only the mineral soil. The sample is reweighed to determine the OM%. Gardeners who add lots of organic matter to their soils may be surprised that the OM content is less than 5%. This is because OM is lighter than mineral soil and the measurement is based on weight, not volume. CEC- cation exchange capacity measures the capacity of a soil to hold and release nutrient ions. Soils high in clay and organic <br />
matter will have high CEC. This measurement will vary across Maryland soils. Adding organic matter is recommended where the CEC is less than 10.</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"><b>Nitrogen</b><br />
<br />
</div><div style="text-align: justify;">Plants need a relatively large amount of nitrogen for healthy growth. Plant roots take up nitrogen in the <br />
nitrate and ammonium forms. Unlike most other nturients, nitrogen does not come from mineral soil. Instead it comes “naturally” from organic matter, lightning and legumes (plants that convert nitrogen in air to nitrate nitrogen.)</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"><b>Fertilizing Responsibly for a Healthy Chesapeake Bay</b></div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;">Nitrogen and phosphorous are the two key nutrient pollutants of waterways in Maryland that contribute to the complex problem known as eutrophication. These nutrients encourage blooms of algae that cloud the water and block sunlight causing underwater grasses to die. This has negative affects on aquatic life and birds. Huge numbers of microorganisms in the water then use up oxygen as they feed on and break down the algae once it has died. Dissolved oxygen in the water quickly declines, depriving fsh, crabs and other aquatic life forms of needed oxygen.It is estimated that up to 80% of the nitrogen entering groundwater and surface water comes from non-point sourcesfarms, public lands, and private landscapes. About one-half of excessive or mis-applied nitrogen fertilizer enters surface water fairly quickly as run-off from hard surfaces, lawns and gardens. The other half travels for at least 10 years through soil and underground water before it eventually enters the Chesapeake Bay (for Marylanders who live east of the Eastern Continental <br />
Divide, located in Garrett County).</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;">So mistakes in measuring and applying fertilizers today can contribute to nutrient pollution problems many years in the future.Farmers, municipalities, corporations, AND homeowners all have a duty to reduce the fow of nitrogen and phosphorous into streams, rivers, and the Chesapeake Bay. Marylanders with lawns should be careful to drastically reduce or eliminate phosphorous fertilization if their soil test results show phosphorous (phosphate) levels that are “adequate”, “optimum”, or “excessive”. The following companies offer lawn fertilizers that contain no phosphorous or a low percentage (3%-5%) of phosphorous: Lebanon-Seaboard (Greenview), Espoma, LESCO, Scotts. </div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"><b>10 Ways to Achieve a Healthy Home Landscape Without Harming the Chesapeake Bay</b></div><div style="text-align: justify;"><br />
</div><ol style="text-align: justify;"><li>Take a soil test every 3 to 4 years. Fertilize according tosoil test recommendations. Use less than the recommended amounts listed on fertilizer packages.</li>
<li>Leave grass clippings on your lawn (grasscycling.) They are a source of nitrogen for your lawn and will not contribute to thatch build-up in fescue or bluegrass lawns.</li>
<li>Home gardeners tend to over-fertilize fower and vegetable gardens. Reduce or eliminate fertilizer applications in wellestablished beds if organic matter is being added each year. </li>
<li>Don’t fertilize trees and shrubs if they appear healthy and are making adequate shoot and leaf growth.Compost plant residues or incorporate them directly into soil. </li>
<li>Discard plants with serious disease problems.</li>
<li>When appropriate, substitute slow-release fertilizers for those that are highly soluble and substitute locally available organic fertilizers (well-decomposed farmyard manure, backyard compost and municipal leaf compost) for manufactured chemical fertilizers.</li>
<li>Keep fertilizers off hard surfaces. Rain water will carry fertilizer salts into storm drains and surface waters and contribute to nutrient pollution of our waterways. </li>
<li>Over time, rainfall causes bare soil to erode and become compacted. Keep bare soil covered with a mulch and plant ground covers in areas where turf won’t grow. Plant winter cover crops in vegetable gardens - like oats, winter rye and crimson clover. </li>
<li>Avoid excessive foot or equipment traffc to prevent soil compaction, especially when the soil is wet. Construct terraces for beds on sloped ground. Keep soil in raised beds framed with solid sides. </li>
<li>To melt winter ice, use calcium magnesium acetate (CMA), potassium chloride (KCl), sodium chloride (NaCl) or calcium chloride (CaCl2). Do not use urea, potassium nitrate, or other chemical fertilizers containing nitrogen or phosphorous. The salts in these fertilizers may burn the foliage and roots of adjacent plants and wash into and pollute waterways.</li>
</ol><i><b>Feed The Soil First!</b></i><br />
The surest way to improve soil quality and plant growth is the regular incorporation of organic matter such as composted yard waste. Organic matter improves soil structure, slowly releases nutrients, increases benefcial microbial activity, and reduces the need for purchased fertilizers<br />
<br />
<div style="text-align: right;"><span style="font-size: x-small;"><i>Authors : Jon Traunfeld, Regional Specialist, Home and Garden <br />
Information Center, Maryland Cooperative Extension<br />
Reviewers: Patricia Steinhilber, Ph.D., Nutrient Management <br />
Coordinator, Maryland Cooperative Extension and Judy <br />
McGowan, Nutrient Management Specialist, Maryland <br />
Department of Agricultur</i></span></div>mayaisjakahttp://www.blogger.com/profile/11820472336428156095noreply@blogger.com0tag:blogger.com,1999:blog-581689683275924296.post-58712782909892900922010-01-28T20:21:00.000-08:002010-06-01T21:26:41.422-07:00Soil Testing Q & A<div style="text-align: justify;"><b>Soil testing</b>... if you feel as though you have heard enough about soil sampling, you are in for a big surprise. With the increased focus on nutrient management planning of intensive livestock areas, and farm planning programs to manage fertilizer nutrients, we are on the verge of major soil sampling promotional campaigns in most provinces. For the average grower, fertilizer cost is also becoming a major challenge in budgetting for crop inputs. Soil testing is an excellent way to minimize the ‘guesswork’ associated with seeding a crop for maximum economic yield. This fertilization article reviews some of the common questions posed each year from crop advisers who take and interpret soil samples.</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"><b>Collecting a good custom soil sample</b> – why is it still a challenge? It has been said a thousand times, soil sampling practices are where the vast majority of errors occur. If you consider that the sample is subject to accepted North American handling protocols once it reaches the soil testing laboratory, any field sampling problem that affects the sample ahead of time will impact the results obtained and thus the recommendations made. For the sake of keeping a customer and getting them used to the best science- based soil fertility planning tool, be sure you are getting good samples.</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"><b>Why is it important to consult with</b>, or take along, the farmer when custom soil sampling? The potential for sampling the ‘wrong’ location is very high in a field you have never been in before, trying to decide the best location to collect your soil cores. With the farmer riding along, or providing clear direction on paper ahead of time, the sample operator has clear guidance as to where not to sample in the field. This becomes critical, considering the time and effort required to collect soil samples and the need for composite samples to be representative of the dominant production area in the field. Once these preferred sampling areas have been identified, marking them with GPS allows for future reference when sampling again.</div><div style="text-align: justify;"><br />
</div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjie04G1mRLjaoDLNaH9sWZLI2_KSvda5bdv8vBGYyql7PeQbZ76tToiA3eueXQW5TZHXXSr9ftpCFhYXAqhmJsziGdbZsi71YD4NECGxFi6CnPdN8JOv8tKlUP9blRblPBVAMw7FZCkMyr/s1600-h/Untitled-3.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjie04G1mRLjaoDLNaH9sWZLI2_KSvda5bdv8vBGYyql7PeQbZ76tToiA3eueXQW5TZHXXSr9ftpCFhYXAqhmJsziGdbZsi71YD4NECGxFi6CnPdN8JOv8tKlUP9blRblPBVAMw7FZCkMyr/s320/Untitled-3.jpg" /></a></div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;">Why do we insist that for a composite sample the operator collect 15 to 20 sample cores? When composite sampling, getting a representative sample is critical. While a composite sample will not provide any insight into the variability found in a particular field, picking the right spots to represent the average production areas is critical. In collecting the sample, imagine what happens to the average value when one bad core (saline for instance) ends up mixed in with the rest. The more samples collected, the more dilution will occur from this one bad core.</div><div style="text-align: justify;"><br />
</div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjApVtLhqMzGSNTMF_ldAmlAuLTLlNfFupuWMa4cAW36r6wkvuHehtseDn6b7RXiu5Hj7uV1Lpx-AXZdycVudE0f-Bvm2cYbVEVdf8Cvf-4EdkvR9oHb5jHQ2n8UwiMBxUyZS4kdZlRZQl5/s1600-h/Untitled-3.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="156" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjApVtLhqMzGSNTMF_ldAmlAuLTLlNfFupuWMa4cAW36r6wkvuHehtseDn6b7RXiu5Hj7uV1Lpx-AXZdycVudE0f-Bvm2cYbVEVdf8Cvf-4EdkvR9oHb5jHQ2n8UwiMBxUyZS4kdZlRZQl5/s400/Untitled-3.jpg" width="400" /></a></div><div style="text-align: justify;"><br />
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</div><div style="text-align: justify;">For example, there are saline areas in many fields in semi-arid regions. However, when you get a soil sample back saying the field is saline, not just the three acres at the base of the hill you have always known about, you know that it is a poor representative sample for the field. One bad core mixed in with eight to 10 others is a far bigger problem than one bad core mixed in with 15 to 20 cores. If the differing areas of the field are large, they should be separated into a sub-region and a sample collected from that particular region. This will aid in fertilizer application rate management. Sample number, or intensity in a field, should increase with the amount of rainfall received, or where irrigation is used.</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"><b>Sampling around last year’s fertilizer bands – how do you avoid high residual nutrients?</b> Selecting a sampling location to collect your soil cores also requires asking how fertilizer P and K were applied the year</div><div style="text-align: justify;">before. While most N and S sources are mobile in the soil and move away from the band location in soil water, P and K additions will remain very close to their original band location. If applied in the seedrow, or in a side-band, these are areas to avoid sampling. Sometimes growers will apply P and K in the mid-row band with their N and S, so these areas should also be avoided. A few simple questions can avoid excessively high soil nutrient levels which end up reducing confidence in the sample collected.</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"><b>How does sampling to a uniform depth avoid disappointment?</b> Nutrient concentration in the soil canvary significantly with soil depth. Care must be taken when collecting a composite sample to ensure that the sampling depth is uniform, and if different from the option provided on the sample bags, this is noted. For </div><div style="text-align: justify;">example, if the laboratory suggests a sampling depth of zero to six inches and six to 24 inches, but you actually have samples that are zero to four inches and four to 16 inches, noting this on the sample bags will ensure that the laboratory uses the appropriate conversion factors when estimating the supply of available nutrients. A change in the depth you submit to the laboratory is not a problem, it is just ensuring that you note on the sample bag what depth the sample was collected.</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"><div style="text-align: justify;"><b>Sample timing – Why is it important to sample at the same time each year?</b></div><div style="text-align: justify;">One of the advantages that soil sampling provides is the opportunity to monitor soil nutrient changes and trends over time. However, to make a good comparison it requires sampling from the same areas from year to year, and sampling at the same time of year. Taking samples for spring seeded crops after fall harvest is ideal. Sampling in the fall prior to any tillage helps to minimize field variability and ensures uniform sample core collection. Canola and pulse fields should be sampled later in the fall once soil temperatures drop below 50 degrees F (10 degrees C), while all cereal stubbles can be sampled after crop harvest. Where possible, avoid sampling frozen soils. Spring is also a good time to sample, with the laboratories offering rapid turn-aroundin sample handling.</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"><b>Composite versus site-specific sampling, what are the advantages?</b> One of the ways in which some farmers have changed their soil sampling practices to minimize variability from year to year is to move to site-specific sampling. Using GPS, they establish a series of four or five co-ordinates in their fields which they believe best represent the field average. These are then provided to the sample operator, who drives to these locations using a truck-mounted GPS receiver. Once in these locations, the operator drives in a tight circle and collects four to five samples for the composite of 15 to 20 total cores from the field. This avoids sampling areas where problems are known to exist, such as salinity, old yard sites and areas where manure was previously applied. With this site-specific information, the farmer can then make his own changes to application rates based on his past knowledge of crop response in specific areas of the field. </div><div style="text-align: justify;"></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiX3i5EIZofEnFGqYZU0Emi6UhfjvkQed9Tm_fX9PjdYJjhGJrjfTvINh1I_dqc4_AaFXvmgjbHtuUOrVZ0mPiIdGcBEAyxL9Ba9UrMOA8AUwJxK_gLA0WChVf9Uh5ie3eWHfeIRBT0ljEQ/s1600-h/Untitled-3.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="133" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiX3i5EIZofEnFGqYZU0Emi6UhfjvkQed9Tm_fX9PjdYJjhGJrjfTvINh1I_dqc4_AaFXvmgjbHtuUOrVZ0mPiIdGcBEAyxL9Ba9UrMOA8AUwJxK_gLA0WChVf9Uh5ie3eWHfeIRBT0ljEQ/s400/Untitled-3.jpg" width="400" /></a></div><div style="text-align: justify;"></div><div style="text-align: justify;"></div><div style="text-align: justify;">Grid sampling – is it for your farm? Grid sampling has been proposed as a means of obtaining the most accurate picture of soil nutrient variability within fields. This variability can then be managed with nutrient additions to increase field uniformity and uniformity in crop response. Grid sample cells vary in size, ranging from a low of one acre to a high of five acres. In many cases, grid sample results are used to manage less mobile nutrients like P and K. Areas low in P and K can receive more fertilizer, while those areas high in P and K will receive little or no fertilizer addition. From a cost of sampling perspective, grid sampling can be very expensive. While it is not conducted on an annual basis, a five acre acre grid on a 160 acre field would require 32 separate analyses... cost prohibitive for many semi-arid cropping regions. While grid sampling has been shown to be profitable in areas where building soil P and K play a major role in increasing yield level and uniformity, it is not likely to be popular with growers in areas where P and K are applied annually at rates similar to crop removal.</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"><br />
</div></div><div style="text-align: right;"><i><span style="font-size: x-small;">*Dr. Adrian Johnston is Northern<br />
Great Plains region director for<br />
PPI/PPIC. Article reprinted with<br />
permission of PPI/PPIC.</span></i></div><div style="text-align: right;"></div><div style="text-align: right;"><i><span style="font-size: x-small;">Reprinted in Canada from the November 2006 issue of Top Crop Manager (West) magazine with permission of Annex Publishing & Printing Inc </span></i></div><div style="text-align: justify;"><br />
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</div>mayaisjakahttp://www.blogger.com/profile/11820472336428156095noreply@blogger.com0tag:blogger.com,1999:blog-581689683275924296.post-40998370611954568142010-02-15T09:31:00.000-08:002010-06-01T21:26:05.805-07:00Civil and Environmental Applications of Geosynthetics<b>INTRODUCTION</b><br />
<div style="text-align: justify;"><br />
</div><div style="text-align: justify;">Geosynthetics include exclusively manmade polymeric products such as geotextiles, geogrids, geonets, geomembranes, geosynthetic clay liners, and geocomposites. The term “geosynthetic” is used in favor of<br />
geotextiles and geofabrics because </div><ol style="text-align: justify;"><li>additional polymeric products are being developed and used with soils and </li>
<li> the application is becoming more diversified.</li>
</ol>Polypropylene, polyester, polyethylene, polyamide, polyvinyl choride, and polystyrene are the major polymers used to manufacture geosynthetics. It is not the properties of the polymers, but the properties of the final polymeric products that are of interest to civil and environmental engineering applications. Geosynthetics are used as part of the geotechnical, transportation, and environmental facilities. Geosynthetic products perform<br />
<div style="text-align: justify;">five main functions: separation, reinforcement, filtration, drainage, and containment (hydraulic barrier). However, in most applications, geosynthetics typically perform more than one major function.</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"><b>TESTING STANDARDS AND DESIGN</b></div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"><b>A. Testing Standards</b></div><div style="text-align: justify;">Some basic standards used for geotextiles are adopted from the textile industries. However, geotechnical engineers realized the deficiencies and started to develop<b> </b>the standards relevant to their applications. The American Society for Testing and Materials (ASTM) is one developer of standardized testing procedures for<br />
different geosynthetics. Most testing standards adopted or developed in other countries are outgrowths of ASTM standards. The Geosynthetic Research Institute (GRI) also provides testing standards to serve industrial needs, especially when related ASTM standards have not been developed. GRI standards are usually removed as related ASTM standards become available. ASTM standards, developed under Committee D35 for Geosynthetics, are listed in the Appendix. These standards were developed under several<br />
subcommittees: terminology, mechanical properties, endurance properties, permeability and filtration, geosynthetic clay liners, geosynthetic erosion control, and geomembranes. New standards are constantly being developed. Details of test standards are published in ASTM (2000).<br />
</div><div style="text-align: justify;">While ASTM standards are index tests, many civil engineering designs and applications require the geosynthetic materials to be tested with site-specific soils, with the testing conditions representing those in the field. These kinds of tests are known as performance tests.</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"><b>B. Design by Function</b></div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;">Different organizations, agencies, and manufacturers provide design guidelines for geosynthetic applications. These design methods are determined by cost, specification (design by specification), or function (design by function). Public agencies have widely adopted the design-by-specification method. The minimum required value of the geosynthetic properties used in a particular application is specified. In the design-by-function method, the primary function of the geosynthetic material is identified. The available and required value of the particular property for that function is assessed to give a factor of safety (FS):</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;">FS = allowable property from testing / required property for design</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;">Designs require a factor of safety greater than unity to account for various uncertainties.</div><div style="text-align: justify;"><br />
</div><div style="text-align: right;"><span style="font-size: x-small;">source : Marcel Dekker Inc (Reinforced Soil Engineering)</span></div><div style="text-align: justify;"><br />
</div>mayaisjakahttp://www.blogger.com/profile/11820472336428156095noreply@blogger.com2tag:blogger.com,1999:blog-581689683275924296.post-50199297736079372082010-02-15T09:46:00.000-08:002010-06-01T21:25:25.685-07:00GEOTEXTILES, GEOGRIDS, AND GEONETS/GEOCOMPOSITES<div style="text-align: justify;">Geotextiles are the earliest type of multifunctional geosynthetic material. Their functions include reinforcement, separation, filtration, and drainage. When impregnated, they are used as containment. However, some newly developed products perform better than geotextiles in certain functions. For example, geogrids are developed specifically to tensile reinforce soil, while geonets are used to convey large-capacity flow. Although geotextile may also be made impermeable and used as containment by spraying bitumen or other polymers on it, geomembranes should be considered for a watertight containment system. The functions of geotextiles, geogrids, and geonets are described collectively in this section, where one material can be referred to the other.<br />
</div><div style="text-align: justify;">Geotextile sheets are manufactured from fibers or yarns. Polymers are melted and forced through a spinneret to form fibers and yarns. They are subsequently hardened and stretched. The manufacturing process produces<br />
woven or nonwoven geotextiles. In producing woven fabrics, conventional textile-weaving methodologies are used. For the nonwoven fabrics, the filaments are bonded together by thermal, chemical, or mechanical means (i.e., heating,using resin, or needle-punching).<br />
</div><div style="text-align: justify;">Geogrids are mainly used as tensile reinforcement. Although biaxial geogrids are available, most geogrids are manufactured to function uniaxially. In manufacturing uniaxial geogrids, circular holes are punched on the polymer sheet, which is subsequently drawn to improve the mechanical properties. For biaxial geogrids, square holes are made on the polymer sheet, which is then drawn longitudinally and transversely. For some geogrids, the junctions between the longitudinal and transverse ribs are bonded by heating or knit-stitching.<br />
Geogrid manufactured from yarns are typically coated with a polymer, latex, or bitumen. Geogrids have higher stiffness and strength than most geotextiles. </div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;">The chapter now describes some major applications of geotextiles and related products</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"><b>Reinforcement of Steep Slopes, Retaining Structures, and Embankments</b> </div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;">Geotextiles and geogrids are used to tensile reinforce steep slopes, retaining structures, and embankments constructed over soft foundation (Fig. 1). Sheets of geotextile/geogrid are embedded horizontally in these soil structures. The shear stress developed in the soil mass is transferred to the geotextile sheets as tensile force through friction. The tensile strength of geotextile/geogrid and its frictional resistance with the soil are the primary items required for design.</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;">The tensile strength of geosynthetic is obtained from the wide-width test. The ASTM standard specifies an aspect ratio (width-to-length) of 2 (i.e., 20 cm to10 cm). Soil confinement may increase the stiffness and strength of nonwoven spun-bonded needle-punched geotextile because of the interactions among the fibers, but it has negligible effect on the heat-bonded nonwoven geotextiles and woven geotextiles. Reduction factors (also known as partial factors of safety) are applied considering possible strength reduction of geotextiles by installation damage, creep, chemical and biological actions. Geotextiles may degrade by exposure to ultraviolet rays, high temperature, oxidation, and hydrolysis (when the environment is highly alkaline), but the effect is minimized when buried in soils.</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;">The frictional behavior of a geotextile with site-specific soil must be determined by direct shear tests. Although the ASTM standard specifies a direct shear box with dimensions of 30 cm by 30 cm, the box with a plane area of 10 cm by 10 cm would be adequate for geotextiles. Pullout tests have been proposed in the last few decades for determining the anchorage capacity of geosynthetics; such tests are not relevant in determining the design parameters because they are subject to scale and boundary effects. For embankments and dikes constructed over a soft foundation that lacks bearing capacity and global stability, a layer or more of geotextile is laid at the base of the embankment. Vertical wick drains of geosynthetic composites or sand drains may be used to accelerate consolidation of the soft foundation. </div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;">Geotextiles have also been used in conjunction with the underwater sand capping of contaminated submarine sediments. In these applications, the seam strength may dominate the design.</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;">Both geotextiles and geogrids are used to reinforce steep slopes and retaining walls. For applications where large tensile stiffness and strength of reinforcement are required, geogrids should be used. A large shear box is<br />
required to determine the frictional properties of the geogrid because the aperture size is large relative to the geotextile. Unlike geotextiles, where frictional behavior dominates the interaction with soil, the junction of some geogrids may provide interlocking. As geotextiles are very flexible, they are typically wrapped around the face of the slope or retaining wall and protected by vegetation, gunite, timber face, or concrete panels to prevent degradation by ultraviolet rays and vandalism.<br />
</div><div style="text-align: justify;">Geogrids are increasingly used with modular blocks to provide an aesthetically pleasant wall appearance. As such, the connection between the blocks and geogrids plays an important role in design. The creep and stress relaxation behavior of geogrids are also studied in conjunction with wall design. In the design of reinforced slopes and walls, a limit equilibrium approach is used. The structure is checked for internal and external stabilities. In the internal stability analysis, a failure wedge is postulated and it is tied back into the stable soil zone. An adequate strength and length of reinforcement are secured. Theexternal stability is evaluated in a manner similar to conventional gravity/cantilever wall design. In the external stability analysis, possible modes of failure, such as direct sliding, overturning, and bearing capacity, are evaluated. The seismic design of reinforced slopes and retaining walls has also received wide attention in recent years.</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"><b>Filter and Drainage Layer</b></div><br />
<div style="text-align: justify;">Geotextiles are used to replace granular soil filters in the underdrain, as well as paved and unpaved roads. They are also used as chimney drain in an earth dam and behind retaining walls (Fig. 2). The hydraulic properties are a major consideration in design. The flow rate obtained from the tests is reduced using reduction factors considering soil clogging and blinding, creep reduction of void space, intrusion of adjacent materials into geotextile voids, chemical clogging, and biological clogging.<br />
</div><div style="text-align: justify;">When functioning as a filter, the geotextile sheet is required to retain the soil while possessing adequate permeability to allow cross-plane flow to occur. The permittivity or permeability and apparent opening size or equivalent opening size of the geotextile are used in design. Permittivity is the coefficient of hydraulic conductivity normalized by the thickness of the geotextile. The filter is also expected to function without clogging throughout the lifetime of the system. The gradient ratio test and long-term flow tests may be used to investigate the clogging potential.</div><div style="text-align: justify;"><br />
</div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg_NSUc72R66sOIUAzyik9No00YGBAh0JWH6s6rBuhJf06tV0RTDMPUGaX1ailUVHELo_pbkRIIvMpx2FyxOlIGsi8w1eqS09ntA9tZs_qMaJVmKYIVK0l128zJOABwsGlh93gB4wSoSFa0/s1600-h/Untitled-1.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg_NSUc72R66sOIUAzyik9No00YGBAh0JWH6s6rBuhJf06tV0RTDMPUGaX1ailUVHELo_pbkRIIvMpx2FyxOlIGsi8w1eqS09ntA9tZs_qMaJVmKYIVK0l128zJOABwsGlh93gB4wSoSFa0/s320/Untitled-1.jpg" /></a> </div><div class="separator" style="clear: both; text-align: center;"><br />
</div><div class="separator" style="clear: both; text-align: left;"><b>Figure 2 Geotextile as drainage layer or filter: (a) chimney drain in earth dam; (b) drain behind retaining wall; (c) underdrain; (d) drainage layer in tunnel.</b> </div><div class="separator" style="clear: both; text-align: left;"><br />
</div><div class="separator" style="clear: both; text-align: left;">If the geotextiles (usually nonwoven needle-punched geotextiles) are used as a drainage layer, the in-plane permeability is considered. Because the thickness decreases with increasing normal stress acting on it, the term “transmissivity” is used, where the coefficient of hydraulic conductivity is normalized by the geotextile thickness</div><div class="separator" style="clear: both; text-align: left;"><br />
</div><div class="separator" style="clear: both; text-align: left;"><b>Large-Capacity Flow with Geonets/Geocomposites</b></div><div class="separator" style="clear: both; text-align: left;"><br />
</div><div class="separator" style="clear: both; text-align: justify;">For drainage applications (such as landfills and surface impoundments), geonets and geocomposites are preferable to geotextiles. These are specifically manufactured to allow for large-capacity flow. Geonets have a parallel set of ribs overlying similar sets at various angles for drainage of fluids. Most geonets are manufactured from polyethylene. They are laminated with geotextiles on one or both surfaces to form drainage geocomposites (Fig. 3). Geonets are mostly manufactured from polyethylene; thus they have high resistance to leachate.</div><div class="separator" style="clear: both; text-align: justify;"><br />
</div><div class="separator" style="clear: both; text-align: justify;">In geonets/geocomposites, the flow is no longer laminar, and thus Darcy’s law is invalid. The flow rate is used in lieu of transmissivity or coefficient of hydraulic conductivity to account for the turbulent flow. Because of the large normal stress acting on the plane of geonet/geocomposites, the crushing strength of the core has to be assessed. Geocomposites are sometimes tested with site-specific soils and liquid. A reduction in the flow rate is expected because of the intrusion of the geotextiles into the core. It is also important to ensure that geotextile sheets, if installed along the slope, do not delaminate from the geonets due to shear stress, because geocomposites are installed at a gradient to allow for gravity flow. The drainage systems of a geocomposite are usually constructed for allowance of cleaning by flushing because they are normally subject to biological</div>action.<br />
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</div><div style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhaFN4qcgm2zkg5w8wVXiuCd1zbixXK12Pf2Kk0Vpp_yDQkVvJtBic6f3GsjHEFP9wkwfvAU_jMKrdVe0VFaIPyh3WA_LyPXkHCjt7vWbqXdRFzN-8tT0BvzbArDbVa5bHr9eyb4UhoiSMS/s1600-h/Untitled-1.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhaFN4qcgm2zkg5w8wVXiuCd1zbixXK12Pf2Kk0Vpp_yDQkVvJtBic6f3GsjHEFP9wkwfvAU_jMKrdVe0VFaIPyh3WA_LyPXkHCjt7vWbqXdRFzN-8tT0BvzbArDbVa5bHr9eyb4UhoiSMS/s320/Untitled-1.jpg" /></a> </div><div style="text-align: center;"><b>Figure 3 Geocomposite. </b></div><div style="text-align: center;"><br />
</div><div style="text-align: left;"><b>Separation and Reinforcement in Roadways</b></div><div style="text-align: left;"><br />
</div><div style="text-align: justify;">In the unpaved roads and railways, geotextile separates the subgrade and stonebase/ballast (Fig. 4). The California bearing ratio (CBR) of the soil subgrade may be used to determine if an unpaved road should be designed for separation or for separation and reinforcement. The intrusion of stone aggregates into the soil<br />
subgrade is prevented by the geotextile in a roadway. In a railway, the fine soil particles are stopped from pumping into the stone aggregates. In addition to tensile strength, other mechanical properties of geotextiles, such as resistance to burst, tear, impact, and puncture, are used for designing geotextiles as a separator.<br />
<br />
However, existing practice does not emphasize design when geotextiles are used as a separator compared to reinforcement and drainage applications. For unpaved roadways, the use of geotextile reinforcement results in cost savings because the thickness of stone aggregates may be reduced. In paved roads, the geotextiles may prevent reflective cracking. The geotextile or biaxial geogrids may be placed above the cracked old pavement followed by the asphalt overlays. The life of the overlay is prolonged in the presence of geosynthetic<br />
materials, or a reduced thickness of overlay may be used while keeping the lifetime equivalent to the case without using the geotextile. In addition to preventing reflective cracking, the geosynthetic reinforces the asphalt pavement.</div><div style="text-align: left;"></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgsPEK9oLOWswrlYo1LZ23vP_r2_hWeBNFrQ3Fc7zM87t5zpUAhVczI_g3SsdW9foQ8W1kecxYn_tLvnoHZh9iv8VjiKwzGuN0kfvnF9ZSvV4aADQmM2dPXpJ47l2O3oi3UKlp2OXy52Njv/s1600-h/Untitled-1.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgsPEK9oLOWswrlYo1LZ23vP_r2_hWeBNFrQ3Fc7zM87t5zpUAhVczI_g3SsdW9foQ8W1kecxYn_tLvnoHZh9iv8VjiKwzGuN0kfvnF9ZSvV4aADQmM2dPXpJ47l2O3oi3UKlp2OXy52Njv/s320/Untitled-1.jpg" /></a> </div><div class="separator" style="clear: both; text-align: center;"><b>Figure 4 Geotextile as separator in unpaved roadway. </b></div><div class="separator" style="clear: both; text-align: center;"><br />
</div><div class="separator" style="clear: both; text-align: left;"><b>Coastal and Environmental Protection</b></div><div class="separator" style="clear: both; text-align: justify;">Geotextiles are placed under erosion control structures, such as rock ripraps and precast concrete blocks (Fig. 5a). They are also used as silt fences at construction sites so that the soil particles are arrested from the runoff water. Geotextiles are also used as geocontainers on land or underwater as storage for slurry and for coastal protection. On land, the dredged materials or sands are pumped under pressure into sewn geotextile sheets. The geotextile inflates to form a tube (Fig. 5b). Geotextile tubes are extremely effective in dewatering the high-water-content slurry/sludge by acting as a filter. The geotextile tube may also be used as an alternative to dike and coastal protection. In such applications, the strength and filter characteristics of the geotextile are important design criteria.</div><br />
<div class="separator" style="clear: both; text-align: justify;">Geocontainers are used for the disposal of potentially hazardous dredged materials and offer a more environmental-friendly means of disposing dredged materials offshore. The geotextile sheets are laid at the bottom of dump barges, filled with dredged sediments, and sewn. The containers are then transported to</div>the disposal site and dumped via a split hull barge.<br />
<div style="text-align: left;"><br />
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</div>mayaisjakahttp://www.blogger.com/profile/11820472336428156095noreply@blogger.com7tag:blogger.com,1999:blog-581689683275924296.post-41010012827910497232010-02-07T21:55:00.000-08:002010-02-07T21:55:06.574-08:00Standard Test Procedures Manual - Stratigraphic Holes<b>Standard Test Prosedures Manual</b><br />
Section : <b>SOILS</b><br />
Subject : <b>STRATIGRAPHIC HOLES</b><br />
<br />
<b>SCOPE</b><br />
<ol><li><b>Description of Test : </b>This method covers the sampling of soils from stratigraphic holes. </li>
</ol><br />
<b>APPARATUS AND MATERIALS</b><br />
<b><br />
</b><br />
<b> Equipment</b><br />
<ol><li>A suitable drilling rig equipped with a 150 mm auger.</li>
<li>Suitable bags and sampling containers such as tares to retain the natural moisture <br />
content.</li>
<li>Munsel color chart.</li>
<li>Pocket penetrometer<b></b></li>
</ol><br />
<b>PROCEDURE</b><br />
<br />
<ol style="text-align: justify;"><li><b>Sampling : </b> Drill stratigraphic holes averaging 1.5 km intervals or less depending upon terrainevaluation, along either hubline. The depth of these holes will be pre-determined by the District Materials Engineer or designate, usually a 13.5 m depth is adequate. Record the hole number, station, offset from centerline as shown in Figure 104-1. Drill continuously until each sample depth is reached then pull the auger up rather than twist it to obtain a good sample. Depths usually tested for moisture content are 0.3, 0.9,1.5m and then every 1.5 m until total depth is reached.Color coding and penetrometer readings may be taken when sampling for moisturecontent. Moisture contents are required for topsoil and sand but no gravel. Use STP 205-3 for moisture contents. Record the above information on Figure 104-1 together with any other pertinent remarks such as depth to water table, and depths at which rocks were encountered in the hole. Also include iron staining, odor from organic material, fossils, etc.The technician will inspect every 0.3 m of material to determine any soil changes. If any change occurs, the depth will be recorded. The Drill Operator can usually detect material changes by noting any changes in the rotational pressure gauge.</li>
<li><b>Bagging and Labeling</b> : lace a 3-5 kg sample of each soil type in a paper bag for further testing. Control section, hole number, station, depth and type of material must be written on the bag and written on tag and placed in the bag. If granular material is encountered, take a 4000 g sample every 1.5 m in depth.</li>
</ol><br />
<b>RESULTS</b><br />
<ol><li><b>Reporting Results</b> : Complete as shown in Figure 104-1.</li>
</ol><br />
<b>ADDITIONAL INFORMATION</b><br />
<br />
<ol><li><b>Additional Testing</b> : This information is required to determine if further testing should be completed. All sample and any material changes should be clearly defined and well documented.</li>
<li><b>Geological Soil Symbols</b> : <i>Symbols used for geological soil classification are as follows:</i><br />
<b>TS</b> - Sutherland Till<br />
<b>TB</b> - Battleford Till<br />
<b>TF</b> - Floral Till<br />
<b>u</b> - Subscript to describe an unoxidized till eg: TFu<br />
<b> o</b> - Subscript to describe an oxidized till eg: TFo<br />
<b> Sl</b> - Silt<br />
<b>CL</b> - Clay<br />
<b>SD</b> - Sand<br />
<b>GR</b> - Gravel</li>
</ol><br />
<div style="text-align: center;"><b>FIGURE 104-1</b><br />
<b>TYPICAL FORM FOR A STRATIGRAPHIC HOLE</b><br />
<b>SASKATCHEWAN HIGHWAYS AND TRANSPORTATION</b><br />
<b>STRATIGRAPHIC HOLE</b></div><div style="text-align: left;"><b> </b></div><div class="separator" style="clear: both; text-align: center;"></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEguu4LnpGfNvZSimzDl3AWEZpZOlJ3pRpx69gdOwsBrOq31weQZZ_NxucgYM7XX1KTEW2mUhC3C944rEa0CjfEv_kwmbjljr-pRxRAGWANene8nAi66hGmawZVkxnjNRmDuwOzd-YBxB7nF/s1600-h/Untitled-1.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="221" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEguu4LnpGfNvZSimzDl3AWEZpZOlJ3pRpx69gdOwsBrOq31weQZZ_NxucgYM7XX1KTEW2mUhC3C944rEa0CjfEv_kwmbjljr-pRxRAGWANene8nAi66hGmawZVkxnjNRmDuwOzd-YBxB7nF/s400/Untitled-1.jpg" width="400" /></a></div><div style="text-align: left;"><b> </b></div><b><br />
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<div style="text-align: right;"><i><span style="font-size: xx-small;">source :</span> <span style="font-size: x-small;">highways.gov.sk.ca</span></i></div>mayaisjakahttp://www.blogger.com/profile/11820472336428156095noreply@blogger.com1tag:blogger.com,1999:blog-581689683275924296.post-37723760656877638322010-02-04T19:59:00.000-08:002010-02-04T19:59:58.547-08:00Standard Test Prosedures Manual - Fine and Coarse Aggregate Test Set<b>Standard Test Prosedures Manual</b><br />
Section : <b>SAMPLING </b><br />
Subject : <b>SAMPLING FINE AND COARSE AGGREGATES </b><br />
<br />
<b>SCOPE</b><br />
<ol style="text-align: justify;"><li><b>Description of Test : </b>This method covers the sampling of coarse and fine aggregates for further testing as requiredaybolt viscosity is expressed in units of furol seconds at a specified temperature.</li>
</ol><b>APPARATUS AND MATERIALS</b><br />
<b><br />
</b><br />
<b>Equipment</b><br />
<ol><li>Sampling pan. </li>
<li>Sample scoop. </li>
<li>Sample splitter and receptacles. </li>
<li>Sample bags or containers. </li>
<li>Sample identification tags. </li>
</ol><b>Number and Masses of Field Samples </b><br />
<br />
<div style="text-align: justify;">The required sample size is based on the type and number of tests to which the material is to be subjected. Amounts specified in Table No. 1 will provide adequate material for routine testing and quality analysis. For routine control, take one sample for every 2 hours of plant production. <b></b></div><div style="text-align: justify;"><b><br />
</b></div><div style="text-align: center;"><b>TABLE 1 <br />
GUIDE FOR SAMPLE SIZE </b></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiLxGORsUsBOAunOYTyGCjgrhfAVFXe5Gkmf2q84aTniPbs5ZMdCthkhl9xo4O-M4HwlBvR1bh6S3O5LGstZz5Gxo32IydMQiKqvf6QKQolo4J_1O5YOTY-1v5gDHaxSd4akh_oB7yca82J/s1600-h/Untitled-1.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="142" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiLxGORsUsBOAunOYTyGCjgrhfAVFXe5Gkmf2q84aTniPbs5ZMdCthkhl9xo4O-M4HwlBvR1bh6S3O5LGstZz5Gxo32IydMQiKqvf6QKQolo4J_1O5YOTY-1v5gDHaxSd4akh_oB7yca82J/s400/Untitled-1.jpg" width="400" /></a> </div><div class="separator" style="clear: both; text-align: left;"><br />
</div><div class="separator" style="clear: both; text-align: left;">Samples will be reduced at the laboratory to testing size with the use of a sample splitter or by the quartering method. </div><div class="separator" style="clear: both; text-align: left;"><br />
</div><div class="separator" style="clear: both; text-align: left;"><b>Shipping Samples </b></div><div class="separator" style="clear: both; text-align: justify;">Transport aggregates in bags or containers that are constructed to prevent loss or contamination of any part of the sample, or damage to the contents from mishandling during shipment. Enclose complete identification with the sample to facilitate reporting of test results. </div><div class="separator" style="clear: both; text-align: left;"><br />
</div><div class="separator" style="clear: both; text-align: left;"><b>PROCEDURE </b></div><div class="separator" style="clear: both; text-align: left;"><br />
</div><ol style="text-align: justify;"><li><b>Sampling from the Conveyor Belt.</b> Obtain at least three approximately equal increments selected at random from the unit or ot being sampled and combine to form a field sample whose mass equals or exceeds the minimum recommended in Table No. 1. Stop the conveyor belt while the sample increments are being obtained. Select a representative section in the middle of the belt. Remove enough material from within the selected section such that the material contained will yield the required <br />
weight. Carefully place all material into a container. </li>
<li><b>Sampling from a Flowing Aggregate Stream (Bins or Belt Discharge)</b>. Select samples by random method from the production. Sample from belt discharge only when plant is operating at normal capacity. Sample from bin discharge only when bins are nearly full in order to minimize change of obtaining segregated material. Obtain at least three approximately equal increments, at random and combine to form a field sample whose mass equals or exceeds the minimum recommended in Table No. 1. Take each increment from the entire cross section of the material as it is being discharged. For larger plants, a special sampling device may have to be constructed on site in order to accomplish the above requirement. A rail or pivot system should be constructed to convey a sampling pan through the discharge stream at a uniform rate. The pan must be large enough to intercept the entire flow and hold the required amount of sample without over flowing. </li>
<li><b>Sampling In Place On Road (Bases and Subbases)</b> . Select sample blocks or areas from completed construction work representing 500 t of production, or in accordance with respective contact specifications. Use a random method to select a representative sample from at least 3 sites within the area to be tested. Combine all 3 samples to form a single field sample that can be reduced as required to the specified size in accordance with the respective contract specifications and test procedures. Clearly mark the specific areas from which the increment is removed. A metal template placed over the area is a definite aid in securing approximately equal increment weights.Take all samples from the roadway for the full depth of the material, taking care to exclude any underlying material. </li>
<li style="text-align: justify;"><b>Sampling From Windrow </b>. Select sample blocks or areas from completed construction work representing 500 t of production, or in accordance with respective contract specification. Use a random method to select a representative sample from at least 3 sites within the areas to be tested. Combine all 3 samples to form a single field sample that can be reduced as required to the specified size in accordance with the respective contract specifications and test procedures.</li>
</ol><b>ADDITIONAL INFORMATION </b><br />
<br />
<div style="text-align: justify;">Aggregate samples may be taken for one of several reasons such as preliminary investigation of the source of supply, to control the product at the source of supply or to control operations at the site and to accept or reject material. <br />
<br />
Sampling is equally as important as the testing and the sampler must use every precaution to obtain samples which will show the true nature and condition of the materials which they represent. Sampling from the initial or final material discharge from a conveyor belt or a bin increases the chances of segregation and should be avoided. The samples are to be taken while the plant is in full operation. <br />
<br />
Samples for preliminary investigation testing are obtained by the party responsible for the development of the potential source (e.g. Gravel Investigation). Where practical, samples to be tested for quality should be obtained from the finished product. </div><div style="text-align: justify;"><br />
</div><div style="text-align: right;"><span style="font-size: x-small;">source : www.highways.gov.sk.ca</span></div><div style="text-align: justify;"><b><br />
</b></div><br />
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<b><br />
</b>mayaisjakahttp://www.blogger.com/profile/11820472336428156095noreply@blogger.com0tag:blogger.com,1999:blog-581689683275924296.post-35549887333371223582010-02-01T21:20:00.000-08:002010-02-01T21:20:12.097-08:00Standard Test Prosedures Manual - Marshal Stability and Flow - Asphalt Mixes<b>Standard Test Prosedures Manual</b><br />
Section : <b>ASPHALT MIXES</b><br />
Subject : <b>MARSHALL STABILITY AND FLOW </b><br />
<br />
<b>SCOPE</b><br />
<br />
<ol style="text-align: justify;"><li><b>Description of Test </b>This method covers the measurement of resistance to plastic flow of cylindrical specimens of asphalt mixtures loaded on the lateral surface by means of the Marshall apparatus. This method is for use with mixtures containing asphalt cement, asphalt cutback, and aggregate up to 25.4 mm maximum size.<b> </b></li>
<li><b>Application of Test</b>. The testing section of this method can also be used to obtain maximum load and flow for asphalt concrete specimens cored from pavements or prepared by STP 204-8, Preparation of Marshall Compaction Specimens.</li>
<li><b>Units of Measure</b> .Stability is measured in Newtons. Flow is measured in mm</li>
</ol><div style="text-align: justify;"><b>APPARATUS AND MATERIALS</b></div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"><b>Equipment Required</b></div><ol style="text-align: justify;"><li><b>Breaking Head</b> - the breaking head shall consist of upper and lower cylindrical segments or test heads having an inside radius of curvature of 50.8 mm accurately machined. The lower segment shall be mounted on a base having two perpendicular guide rods or posts extending upward. Guide sleeves in the upper segment shall be in such a position as to direct the two segments together without appreciable binding or lose motion on the guide rods.</li>
<li><b>Loading Jack</b> - the loading jack shall consist of a screw jack mounted in a testing frame and shall produce a uniform vertical movement of 50.8 mm/minute. An electric motor may be attached to the jacking mechanism.</li>
<li><b>Ring Dynamometer Assembly or Electronic Equivalent</b> - one ring dynamometer of 2267 kg capacity and sensitivity of 4.536 kg up to 453.6 kg and 11.34 kg between 453.6 and 2267 kg shall be equipped with a micrometer dial. The micrometer dial shall be graduated in 0.0025 mm. Upper and lower ring dynamometer attachments are required for fastening the ring dynamometer to the testing frame and transmitting the load to the breaking head.</li>
<li><b>Flowmeter</b> - the flowmeter shall consist of a guide sleeve and a gauge. The activating pin of the gauge shall slide inside the guide sleeve with a slight amount of frictional resistance. The guide sleeve shall slide freely over the guide rod of the breaking head. The flowmeter gauge shall be adjusted to zero when placed in position on the breaking head when each individual test specimen is inserted between the breaking head segments.</li>
<li><b>Water Bath</b> - the water bath shall be at least 152 mm deep and shall be thermostatically controlled so as to maintain the bath at 60 ± 1o C. The tank shall have a perforated false bottom or be equipped with a shelf for supporting specimens 51 mm above the bottom of the bath.</li>
<li><b>Air Bath</b> - the air bath for asphalt cutback mixtures shall be thermostatically controlled and shall maintain the air temperature at 25 ± 1o C</li>
</ol><b>Materials Required</b><br />
<ol><li>Samples may include cored specimens, field or lab prepared specimens</li>
</ol><b>Sample to be Tested</b><br />
<ol style="text-align: justify;"><li>Density of the specimen is required to obtain the volume for a correlation ratio. Density can be determined as outlined in STP 204-21, DENSITY AND VOID CHARACTERISTICS.</li>
</ol><b>PROCEDURE</b> :<br />
<br />
<b>Equipment Preparation</b><br />
Thoroughly clean the guide rods and the inside surfaces of the test heads prior to making the test, and lubricate the guide rods so that the upper test head slides freely over them.<br />
<br />
<b>Sample Preparation</b><br />
Samples will be prepared in accordance with STP 204-8, Preparation of Marshall Compaction Specimens or collected in accordance with STP 204-5, Asphalt Concrete Samples Obtained by Coring.<br />
<br />
<b>Test Procedure</b><br />
<br />
<div style="text-align: justify;">Bring the specimens prepared with asphalt cement to the specified temperature by immersing in a water bath 30 minutes. Maintain the bath or oven temperature at 60 ± 1o C for asphalt cement specimens. Bring the specimens prepared with asphalt cutback to the specified temperature by placing them in the air bath for a minimum of 2 hours. Maintain the air bath temperature at 25 ± 1o C. The testing head temperature shall be maintained between 20 to 38o C. Remove the specimen from the water bath, oven or air bath and place in the lower segment at the breaking head. Place the upper segment of the breaking head on the specimen and place the complete assembly in position on the testing machine. Place the flowmeter, where used, in position over one of the guide rods and adjust the flowmeter to zero while holding the sleeve firmly against the upper segment of the breaking head. </div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;">Hold the flowmeter sleeve firmly against the upper segment of the breaking head while the test load is being applied. Apply the load to the specimen by means of the constant rate of movement of the load jack or testing machine head of 50.8 mm/minute until the maximum load is reached and the load decreases as indicated by the dial. Record the maximum load noted on the testing machine or converted from the maximum micrometer dial reading. Release the flowmeter sleeve or note the micrometer dial reading, where used, the instant the maximum load begins to decrease. Note and record the indicated flow value or equivalent units in mm if a micrometer dial is used to measure the flow. The elapsed time for the test from removal of the test specimen from the water bath to the maximum load determinations shall not exceed 30 seconds. </div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"><b>RESULTS & CALCULATIONS</b></div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"><b>Collection of Test Results</b><br />
For specimens other than 63.5 mm in thickness correct the load by using the proper multiplying factor from Table 1. The reports shall include the following information:</div><ol><li>Type of sample tested (lab sample or pavement core specimen). For core specimens the height of each test specimen in mm shall be reported.</li>
<li>Average maximum load in newtons, corrected when required.</li>
<li>Average flow value in millimetres.</li>
<li>Test temperature</li>
</ol>TABLE 1 - Stability Correlation Ratios*<br />
Volume of Specimen Thickness of Specimen Correlation Ratio<br />
(cm3) (mm)<br />
200 to 213 25.4 5.56<br />
214 to 225 27.0 5.00<br />
225 to 237 28.6 4.55<br />
238 to 250 30.2 4.17<br />
251 to 264 31.8 3.85<br />
265 to 276 33.3 3.57<br />
277 to 289 34.9 3.33<br />
290 to 301 36.5 3.03<br />
302 to 316 38.1 2.78<br />
317 to 328 39.7 2.50<br />
329 to 340 41.3 2.27<br />
341 to 353 42.9 2.08<br />
354 to 367 44.4 1.92<br />
368 to 379 46.0 1.79<br />
380 to 392 47.6 1.67<br />
393 to 405 49.2 1.56<br />
406 to 420 50.8 1.47<br />
421 to 431 52.4 1.39<br />
432 to 443 54.0 1.32<br />
444 to 456 55.6 1.25<br />
457 to 470 57.2 1.19<br />
471 to 482 58.7 1.14<br />
483 to 495 60.3 1.09<br />
496 to 508 61.9 1.04<br />
509 to 522 63.5 1.00<br />
523 to 535 64.0 0.96<br />
536 to 546 65.1 0.93<br />
547 to 559 66.7 0.89<br />
560 to 573 68.3 0.86<br />
574 to 585 71.4 0.83<br />
586 to 598 73.0 0.81<br />
599 to 610 74.6 0.78<br />
611 to 625 76.2 0.76<br />
<br />
The measured stability of a specimen multiplied by the ratio for the thickness of the specimen equals the corrected stability for a 63.5 mm specimen.<br />
<br />
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</div>mayaisjakahttp://www.blogger.com/profile/11820472336428156095noreply@blogger.com2tag:blogger.com,1999:blog-581689683275924296.post-86415042758997690272010-01-18T23:27:00.000-08:002010-01-18T23:27:40.159-08:00Three Types Of Soil Samples Can Be Recovered From BoringsThree Types Of Soil Samples Can Be Recovered From Borings :<br />
<br />
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjC2mbOFeF4q_jXphyphenhyphen_HO5_XLFEQu_P6ONKjl1_UnpekTqpLZbtm42nz7Xrl5lQhgXpc-qEnWa-hF-9tRHdyi7uonIAF-sK6TB2pllT_5-4LZ59zIgefzasq5U_To76Uie5aqcaUDr3QV4C/s1600-h/Untitled-1.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjC2mbOFeF4q_jXphyphenhyphen_HO5_XLFEQu_P6ONKjl1_UnpekTqpLZbtm42nz7Xrl5lQhgXpc-qEnWa-hF-9tRHdyi7uonIAF-sK6TB2pllT_5-4LZ59zIgefzasq5U_To76Uie5aqcaUDr3QV4C/s320/Untitled-1.jpg" /></a><br />
</div><div class="separator" style="clear: both; text-align: center;"><span style="font-size: x-small;">FIGURE 6.1 Soil Samplers (no. 1 is the California Sampler in an open condition,<br />
no. 2 is a Shelby Tube, and no. 3 is the Standard Penetration Test sampler.)</span> <br />
</div><br />
<b>1. Altered Soil.</b><br />
<br />
<div style="text-align: justify;">During the boring operations, soil can be altered due to mixing or contamination. For example, if the boring is not cleaned out prior to sampling, a soil sample taken from the bottom of the borehole may actually consist of cuttings from the side of the borehole. These borehole cuttings, which have fallen to the bottom of the borehole, will not represent in-situ conditions at the depth sampled. In other cases, the soil sample may become contaminated with drilling fluid, which is used for wash-type borings. These types of soil samples that have been mixed or contaminated by the drilling process should not be used for laboratory tests because they will lead to incorrect conclusions regarding subsurface conditions. Soil that has a change in moisture content due to the drilling fluid or heat generated during the drilling operations should also be classified as altered soil. Soil that has been densified by over-pushing or over-driving the soil sampler should also be considered as altered because the process of over-pushing or over-driving could squeeze water from the soil.<br />
</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"><b>2. Disturbed Samples.</b><br />
</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;">Disturbed soil is defined as soil that has been remolded during the sampling process. For example, soil obtained from driven samplers, such as the Standard Penetration Test spilt spoon sampler, or chunks of intact soil brought to the surface in an auger bucket (i.e., bulk samples), are considered disturbed soil. Disturbed soil can be used for numerous types of laboratory tests<br />
</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"><b>3. Undisturbed Sample.</b><br />
</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;">It should be recognized that no soil sample can be taken from the ground in a perfectly undisturbed state. However, this terminology has been applied to those soil samples taken by certain sampling methods. Undisturbed samples are often defined as those samples obtained by slowly pushing thinwalled tubes, having sharp cutting ends and tip relief, into the soil. Two parameters, the inside clearance ratio and the area ratio, are often used to evaluate the disturbance potential of different samplers, and they are defined as follows:<br />
</div><div style="text-align: justify;"><br />
</div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhUnX5hoH1OtAm-zuuPt6oFtNcY2sZL9dqm3QZtbUqZnAMBkNJ_07f2rx6rNGBQ5IcerLylLUythuzyW9yW9dhOJ3lFAfVQl-_FUS70oLqlEadKvKRlS0pqLvgmldAkR9cWZehc7yXbctxf/s1600-h/Untitled-1.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhUnX5hoH1OtAm-zuuPt6oFtNcY2sZL9dqm3QZtbUqZnAMBkNJ_07f2rx6rNGBQ5IcerLylLUythuzyW9yW9dhOJ3lFAfVQl-_FUS70oLqlEadKvKRlS0pqLvgmldAkR9cWZehc7yXbctxf/s320/Untitled-1.jpg" /></a><br />
</div><div style="text-align: justify;">where :<br />
</div><div style="text-align: justify;">De =diameter at the sampler cutting tip<br />
Di = inside diameter of the sampling tube<br />
Do = outside diameter of the sampling tube<br />
</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;">In general, a sampling tube for undisturbed soil specimens should have an inside clearance ratio of about 1% and an area ratio of about 10% or less. Having an inside clearance ratio of about 1% provides for tip relief of the soil and reduces the friction between the soil and inside of the sampling tube during the sampling process. A thin film of oil can be applied at the cutting edge to also reduce the friction between the soil and metal tube during sampling operations. The purpose of having a low area ratio and a sharp cutting end is to slice into the soil with as little disruption and displacement of the soil as possible. Shelby tubes are manufactured to meet these specifications and are considered to be undisturbed soil samplers. As a comparison, the California Sampler has an area ratio of 44% and is considered to be a thick-walled sampler.<br />
</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"> It should be mentioned that using a thin-walled tube, such as a Shelby tube, will not guarantee an undisturbed soil specimen. Many other factors can cause soil disturbance, such as :<br />
</div><div style="text-align: justify;"><br />
</div><ul><li>Pieces of hard gravel or shell fragments in the soil, which can cause voids to develop along the sides of the sampling tube during the sampling process</li>
<li>Soil adjustment caused by stress relief when making a borehole</li>
<li>Disruption of the soil structure due to hammering or pushing the sampling tube into the soil stratum</li>
<li>Expansion of gas during retrieval of the sampling tube</li>
<li>Jarring or banging the sampling tube during transportation to the laboratory</li>
<li>Roughly removing the soil from the sampling tube</li>
<li>Crudely cutting the soil specimen to a specific size for a laboratory test</li>
</ul>he actions listed above cause a decrease in effective stress, a reduction in the interparticle bonds, and a rearrangement of the soil particles. An ‘‘undisturbed’’ soil specimen will have little rearrangement of the soil particles and perhaps no disturbance except that caused by stress relief where there is a change from the in-situ stress condition to an isotropic ‘‘perfect sample’’ stress condition. A disturbed soil specimen will have a disrupted soil structure with perhaps a total rearrangement of soil particles. When measuring the shear strength or deformation characteristics of the soil, the results of laboratory tests run on undisturbed specimens obviously better represent in-situ properties than laboratory tests run on disturbed specimens.<br />
<br />
Soil samples recovered from the borehole should be kept within the sampling tube or sampling rings. The soil sampling tube should be tightly sealed with end caps or the sampling rings thoroughly sealed in containers to prevent a loss of moisture during transportation to the laboratory. The soil samples should be marked with the file or project number, date of sampling, name of engineer or geologist who performed the sampling, and boring number and depth.<br />
<br />
<div style="text-align: right;"><span style="font-size: x-small;">Source : Robert W. Day Chief Engineer, American Geotechnical San Diego, California</span><br />
</div>mayaisjakahttp://www.blogger.com/profile/11820472336428156095noreply@blogger.com5tag:blogger.com,1999:blog-581689683275924296.post-37922898070261017062010-01-18T23:09:00.000-08:002010-01-18T23:14:26.337-08:00Soil Mechanichs And Foundations Building Part.1<b>INTRODUCTION</b><br />
<br />
<b>1. Soil Mechanics</b><br />
<br />
<div style="text-align: justify;">Soil mechanics is defined as the application of the laws and principles of mechanics and hydraulics to engineering problems dealing with soil as an engineering material. Soil has many different meanings, depending on the field of study. For example, in agronomy (application of science to farming), soil is defined as a surface deposit that contains mineral matter that originated from the original weathering of rock and also contains organic matter that has accumulated through the decomposition of plants and animals. To an agronomist, soil is that material that has been sufficiently altered and supplied with nutrients that it can support the growth of plant roots. But to a geotechnical engineer, soil has a much broader meaning and can include not only agronomic material, but also broken-up fragments of rock, volcanicash, alluvium, aeolian sand, glacial material, and any other residual or transported product of rock weathering. Difficulties naturally arise because there is not a distinct dividing line between rock and soil. For example, to a geologist a given material may be classified as a formational rock because it belongs to a definite geologic environment, but to a geotechnical engineer it may be sufficiently weathered or friable that it should be classified as a soil.<br />
</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"><b>2. Rock Mechanics</b><br />
</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"><b>Rock mechanics</b> is defined as the application of the knowledge of the mechanical behavior of rock to engineering problems dealing with rock. To the geotechnical engineer, rock is a relatively solid mass that has permanent and strong bonds between the minerals. Rocks can be classified as being either sedimentary, igneous, or metamorphic. There are significant differences in the behavior of soil versus rock, and there is not much overlap between soil mechanics and rock mechanics.<b> <br />
</b><br />
</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"><b>3.Foundation Engineering</b><br />
</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;">A foundation is defined as that part of the structure that supports the weight of the structure and transmits the load to underlying soil or rock. Foundation engineering applies the knowledge of soil mechanics, rock mechanics, geology, and structural engineering to the design and construction of foundations for buildings and other structures. The most basic aspect of foundation engineering deals with the selection of the type of foundation, such as using a shallow or deep foundation system. Another important aspect of foundation engineering involves the development of design parameters, such as the bearing capacity of the foundation. Foundation engineering could also include the actual foundation design, such as determining the type and spacing of steel reinforcement in concrete footings. As indicated in Table 6.2, foundations are commonly divided into two categories: shallow and deep foundations.<br />
</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"><b><br />
Table 6.1 presents a list of common soil and rock conditions that require special consideration by the geotechnical engineer.</b><br />
</div><div style="text-align: justify;"><br />
</div><div style="text-align: center;">TABLE 6.1 Problem Conditions Requiring Special Consideration <b><br />
</b><br />
</div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgIY4iPx9HMDDSUSii8SfAlTi_ynoUK0Z4sRreSx1f4axGIyk0AmxjMYCjEvoAZ-osgrb5ZwdQlBmxmgHzS7dyHiKVhEAZfcF-8by1YkRSSlAj6ecz2wwsw4qKiFS3R0Yk-gWbOgChkrfoo/s1600-h/Untitled-1.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgIY4iPx9HMDDSUSii8SfAlTi_ynoUK0Z4sRreSx1f4axGIyk0AmxjMYCjEvoAZ-osgrb5ZwdQlBmxmgHzS7dyHiKVhEAZfcF-8by1YkRSSlAj6ecz2wwsw4qKiFS3R0Yk-gWbOgChkrfoo/s640/Untitled-1.jpg" /></a><br />
</div><div style="text-align: center;"><span style="font-size: x-small;">Source: ‘‘Standard Specifications for Highway Bridges,’’ 16th ed., American Association of State Highway and Transporation Officials, Washington, DC.</span><br />
</div><div style="text-align: center;"><br />
</div><div style="text-align: left;"><b>4. FIELD EXPLORATION</b><br />
</div><div style="text-align: left;"><br />
</div><div style="text-align: left;">The purpose of the field exploration is to obtain the following (M. J. Tomlinson, ‘‘Foundation Design and Construction,’’ 5th ed., John Wiley & Sons, Inc., New York)<br />
</div><div style="text-align: left;"><br />
</div><ol><li style="text-align: justify;">Knowledge of the general topography of the site as it affects foundation design and construction, e.g., surface configuration, adjacent property, the presence of watercourses, ponds, hedges, trees, rock outcrops, etc., and the available access for construction vehicles and materials.</li>
<li style="text-align: justify;">The location of buried utilities such as electric power and telephone cables, water mains, and sewers.</li>
<li style="text-align: justify;">The general geology of the area, with particular reference to the main geologic formations underlying the site and the possibility of subsidence from mineral extraction or other causes.</li>
<li style="text-align: justify;">The previous history and use of the site, including information on any defects or failures of existing or former buildings attributable to foundation conditions.</li>
<li style="text-align: justify;">Any special features such as the possibility of earthquakes or climate factors such as flooding, seasonal swelling and shrinkage, permafrost, and soil erosion.</li>
<li style="text-align: justify;">The availability and quality of local construction materials such as concrete aggregates, building and road stone, and water for construction purposes.</li>
<li style="text-align: justify;">For maritime or river structures, information on tidal ranges and river levels, velocity of tidal and river currents, and other hydrographic and meteorological data.</li>
<li style="text-align: justify;">A detailed record of the soil and rock strata and groundwater conditions within the zones affected by foundation bearing pressures and construction operations, or of any deeper strata affecting the site conditions in any way.</li>
<li style="text-align: justify;">Results of laboratory tests on soil and rock samples appropriate to the particular foundation design or construction problems.</li>
<li style="text-align: justify;">Results of chemical analyses on soil or groundwater to determine possible deleterious effects of foundation structures.</li>
</ol><b>5. Document Review</b><br />
<br />
<div style="text-align: justify;">Some of the required information, such as the previous history and use of the site, can be obtained from a document review. For example, there may be old engineering reports indicating that the site contains deposits of fill, abandoned septic systems and leach fields, buried storage tanks, seepage pits, cisterns, mining shafts, tunnels, or other man-made surface and subsurface works that could impact the new proposed development. There may also be information concerning on-site utilities and underground pipelines, which may need to be capped or rerouted around the project.<br />
</div><br />
<div style="text-align: center;"><span style="font-size: x-small;">TABLE 6.2 Common Types of Foundations </span><br />
</div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhnw94f7-CNz2IWFdtQYIJtRGfEjul41dyNIQF_SguVDD97EUbdXWM5zt2UlelcC1IruxrH_MMIX7-lS74-SBPDVQcgBWpUXFgdjcPTx4fSAZcG1LQWNNMQSC0YCfgjx4LHhIE6oU1cc19X/s1600-h/Untitled-2.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhnw94f7-CNz2IWFdtQYIJtRGfEjul41dyNIQF_SguVDD97EUbdXWM5zt2UlelcC1IruxrH_MMIX7-lS74-SBPDVQcgBWpUXFgdjcPTx4fSAZcG1LQWNNMQSC0YCfgjx4LHhIE6oU1cc19X/s640/Untitled-2.jpg" /></a><br />
</div><br />
<div style="text-align: center;"><span style="font-size: x-small;">TABLE 6.2 Common Types of Foundations (Continued) </span><br />
</div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgcbcvqkrRgskGkfwhtTCLiOr_-lh3AH7XLojCWxCWb7rVkoSMfziPRsm1iZD5LZDXd6eGPjcAIuEjvSOl0PcYHt-qky3bBta73FZFKu3WhU6aTgmZ1Ef7UMZi0v5xDOIsFpONxZ3kqu2Aa/s1600-h/Untitled-3.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgcbcvqkrRgskGkfwhtTCLiOr_-lh3AH7XLojCWxCWb7rVkoSMfziPRsm1iZD5LZDXd6eGPjcAIuEjvSOl0PcYHt-qky3bBta73FZFKu3WhU6aTgmZ1Ef7UMZi0v5xDOIsFpONxZ3kqu2Aa/s640/Untitled-3.jpg" /></a><br />
</div><br />
<div style="text-align: justify;">During the course of the work, it may be necessary to check reference materials, such as geologic and topographic maps. Geologic maps can be especially useful because they often indicate potential geologic hazards (e.g., faults, landslides) as well as the type of near-surface soil or rock at the site. Both old and recent topographic maps can also provide valuable site information. Topographic maps are usually to scale and show the locations of buildings, roads, freeways, train tracks, and other civil engineering works as well as natural features such as canyons, rivers, lagoons, sea cliffs, and beaches. The topographic maps can even show the locations of sewage disposal ponds and water tanks, and by using different colors and shading, they indicate older versus newer development. But the main purpose of the topographic map is to indicate ground surface elevations.<br />
</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;">This information can be used to determine the major topographic features at the site and for the planning of subsurface exploration, such as available site access for drilling rigs. Another important source of information is aerial photographs, which are taken from an aircraft flying at a prescribed altitude along preestablished lines. Viewing a pair of aerial photographs, with the aid of a stereoscope, provides a three dimensional view of the land surface. This view may reveal important geologic information at the site, such as the presence of landslides, fault scarps, types of landforms (e.g., dunes, alluvial fans, glacial deposits such as moraines and eskers), erosional features, general type and approximate thickness of vegetation, and drain-<br />
age patterns. By comparing older versus newer aerial photographs, the engineering geologist can also observe any man-made or natural changes that have occurred at the site.<br />
</div><br />
<b>6. Subsurface Exploration</b><br />
<br />
<div style="text-align: justify;">In order for a detailed record of the soil and rock strata and groundwater conditions at the site to be determined, subsurface exploration is usually required. There are different types of subsurface exploration, such as borings, test pits, and trenches. Table 6.3 summarizes the boring, core drilling, sampling, and other exploratory techniques that can be used by the geotechnical engineer.<br />
<br />
</div><div style="text-align: justify;">A boring is defined as a cylindrical hole drilled into the ground for the purposes of investigating subsurface conditions, performing field tests, and obtaining soil,rock, or groundwater specimens for testing. Borings can be excavated by hand (e.g., with a hand auger), although the usual procedure is to use mechanical equipment<br />
to excavate the borings. Many different types of equipment are used to excavate borings. Typical types<br />
of borings are listed in Table 6.3 and include:<br />
</div><div style="text-align: justify;"><br />
</div><ul style="text-align: justify;"><li><b>Auger Boring.</b> A mechanical auger is a very fast method of excavating a boring. The hole is excavated by rotating the auger while at the same time applying a downward pressure on the auger to help obtain penetration of the soil or rock. There are basically two types of augers: flight augers and bucket augers. Common available diameters of flight augers are 5 cm to 1.2 m (2 in to 4 ft) and of bucket augers are 0.3 m to 2.4 m (1 ft to 8 ft). The auger is periodically removed from the hole, and the soil lodged in the groves of the flight auger or contained in the bucket of the bucket auger is removed. A casing is generally not used for auger borings, and the hole may cave-in during the excavation of loose or soft<br />
soils or when the excavation is below the groundwater table. Augers are probably the most common type of equipment used to excavate borings. <br />
</li>
<li><b>Hollow-Stem Flight Auger.</b> A hollow-stem flight auger has a circular hollow core which allows for sampling down the center of the auger. The hollow-stem auger acts like a casing and allows for sampling in loose or soft soils or when the excavation is below the groundwater table.</li>
<li><b>Wash-Type Borings.</b> Wash-type borings use circulating drilling fluid, which removes cuttings from the borehole. The cuttings are created by the chopping, twisting, and jetting action of the drill bit, which breaks the soil or rock into small fragments. Casings are often used to prevent cave-in of the hole. Because drilling fluid is used during the excavation, it can be difficult to classify the soil and obtain uncontaminated soil samples. Rotary Coring. This type of boring equipment uses power rotation of the drilling bit as circulating fluid removes cuttings from the hole. Table 6.3 lists various types of rotary coring for soil and rock.</li>
<li><b>Percussion Drilling. </b>This type of drilling equipment is often used to penetrate hard rock, for subsurface exploration or for the purpose of drilling wells. The drill bit works much like a jackhammer, rising and falling to break up and crush the rock material.</li>
</ul><div style="text-align: justify;">In addition to borings, other methods for performing subsurface exploration include test pits and trenches. Test pits are often square in plan view, with a typical dimension of 1.2 m by 1.2 m (4 ft by 4 ft). Trenches are long and narrow excavations usually made by a backhoe or bulldozer. Table 6.4 presents the uses, capabilities, and limitations of test pits and trenches. Test pits and trenches provide for a visual observation of subsurface conditions. They can also be used to obtain undisturbed block samples of soil.<br />
</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;">The process consists of carving a block of soil from the side or bottom of the test pit or trench. Soil samples can also be obtained from the test pits or trenches by manually driving Shelby tubes, drive cylinders, or other types of sampling tubes into the ground. (See Art. 6.2.3.) Backhoe trenches are an economical means of performing subsurface exploration. The backhoe can quickly excavate the trench, which can then be used to observe and test the in-situ soil. In many subsurface explorations, backhoe trenches are used to evaluate near-surface and geologic conditions (i.e., up to 15 ft deep), with borings being used to investigate deeper subsurface conditions.<br />
</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"><b>7. Soil Sampling</b><br />
</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;">Many different types of samplers are used to retrieve soil and rock specimens from the borings. Common examples are indicated in Table 6.3. Figure 6.1 shows three types of samplers, the ‘‘California Sampler,’’ Shelby tube sampler, and Standard Penetration Test (SPT) sampler. The most common type of soil sampler used in the United States is the Shelby tube, which is a thin-walled sampling tube. It can be manufactured to different diameters and lengths, with a typical diameter varying from 5 to 7.6 cm (2 to 3 in) nd a length of 0.6 to 0.9 m (2 to 3 ft). The Shelby tube should be manufactured to meet exact specifications, such as those stated by ASTM D 1587-94 (1998).<br />
</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;">The Shelby tube shown in Fig. 6.1 has an inside diameter of 6.35 cm (2.5 in). Many localities have developed samplers that have proven successful with local soil conditions. For example, in southern California, a common type of sampler is the California Sampler, which is a split-spoon type sampler that contains removable internal rings, 2.54 cm (1 in) in height. Figure 6.1 shows the California Sampler in an open condition, with the individual rings exposed. The California Sampler has a 7.6-cm (3.0 in) outside diameter and a 6.35-cm (2.50-in) inside diameter. This sturdy sampler, which is considered to be a thick-walled sampler, has proven successful in sampling hard and desiccated soil and soft sedimentary rock common<br />
in southern California.<br />
</div><div style="text-align: justify;"><br />
</div><div style="text-align: right;"><span style="font-size: xx-small;">source : Robert W. Day Chief Engineer, American Geotechnical San Diego, California</span><br />
</div>mayaisjakahttp://www.blogger.com/profile/11820472336428156095noreply@blogger.com4tag:blogger.com,1999:blog-581689683275924296.post-67504433995878105362010-01-18T00:25:00.000-08:002010-01-18T00:25:35.845-08:00USE OF CONE PENETRATION TEST IN PILE DESIGN<b>USE OF CONE PENETRATION TEST IN PILE DESIGN</b><br />
<br />
<b>Introduction</b><br />
<br />
The prediction of pile capacity is complicated by the large variety of soil types and installation procedures. Many methods have been proposed to predict the axial capacity of single piles. These methods can be divided in three main groups:<br />
<br />
<ol><li>Full scale pile load test: This test exactly describes the piles behaviour with a load-settlement curve. At the moment this is the best method to predict the capacity of a single pile. The disadvantages of this method are: the costs of such a test are high, and it is rarely feasible in the stage of planning.</li>
<li>Calculation methods based on results of laboratory tests: The low accuracyof these methods makes their economical use difficult.</li>
<li>Calculation methods based on results of ‘in-situ’ tests: Among the numerous in-situ devices, the cone penetration test (CPT) and the piezocone (CPTu) represent the most versatile tools for geotechnical design. One of the earliest applications of this device was to predict a pile’s axial capacity. As a model pile it is pushed into the ground and measurements are made of the resistance to penetration of the cone. Using this test the pile capacity can be predicted time- and cost-efficiently even in the stage of planning. Nevertheless the accuracy of thismethod will not achieve that of full scale tests, but the reliability of predictions based on CPT is improving.</li>
</ol><b>Test Site </b><br />
<br />
Most of the tests were performed at the construction of highwayM3 in Hungary, but other tests were also performed at different sites in Hungary. The tested piles were CFA (continuous flight auger) piles. The length of the piles ranged from 6.20 m to 22.00 m, the diameter ranged from 0.60 m to 1.00 m. The pile load tests were performed in different soil conditions.<br />
<br />
<b>Interpretation of Pile Load Tests </b><br />
<br />
The ultimate bearing capacity of the tested piles, determined by the method described in the Hungarian Code (MI-04-190), ranged from 830 kN to 3900 kN. The pile axial capacity consists of two components: end bearing load (base resistance) and side friction load (shaft resistance). At the pile load tests only total capacity of the piles is measured, so it was necessary to calculate the base resistance and the shaft resistance of the piles separately, based on the results of the performed tests. These values were determined based on detailed analysis of the test results and soil conditions.<br />
<br />
<b>Prediction of Pile Capacity Using CPT Data</b><br />
<br />
The maximum bearing resistance of each single pile was predicted using the following methods:<br />
• DIN 4014 (German Standard) method<br />
• Bustamante and Giasenelli (1982) method (LCPC method)<br />
• EUROCODE 7-3 method (process recommended by EC 7-3)<br />
• ERTC3 method (De Cock, F. – Legrand C., 1997)<br />
<br />
<div style="text-align: center;">In all cases the pile capacity is derived from the known formula:<br />
</div><div style="text-align: center;"><b>Fmax = Fmax, base + Fmax, shaft ,</b><br />
</div><div style="text-align: center;"><br />
</div><div style="text-align: left;"><b>where: </b><br />
</div><ul><li>Fmax is the maximum bearing resistance of the pile;</li>
<li>Fmax, base is the maximum base resistance;</li>
<li>Fmax, shaft is the maximum shaft resistance;</li>
</ul><div style="text-align: center;">DIN 4014 Method </div><div style="text-align: center;"><br />
</div><div style="text-align: justify;">The German Standard provides different methods for cohesive and non-cohesive soils. In case of non-cohesive soils the unit base and shaft resistance of a bored pile can be calculated using the following tables (Table1, Table 2):</div><div style="text-align: justify;"><br />
</div><div class="separator" style="clear: both; text-align: center;"><br />
</div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhNYnhm_9s8fiEvUzlsrYAF5HlwNWtdmWvb1GQple1uyA8CDr6OEIqYviLs0lzzSV-KOQjC3vTDTWoSYLIZGY341TJwA6E88xZ2FsSc-9PJN7rf1Qjo02JpvJC_t7-un4RMlSH8IVOIox-m/s1600-h/Untitled-2.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhNYnhm_9s8fiEvUzlsrYAF5HlwNWtdmWvb1GQple1uyA8CDr6OEIqYviLs0lzzSV-KOQjC3vTDTWoSYLIZGY341TJwA6E88xZ2FsSc-9PJN7rf1Qjo02JpvJC_t7-un4RMlSH8IVOIox-m/s400/Untitled-2.jpg" /></a><br />
</div><div style="text-align: justify;"><b><br />
</b></div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;">For the calculation of unit base resistance the average cone tip resistance is determined between the pile tip and depth of three times the pile diameter under the tip. In case of cohesive soils the unit base resistance and the unit skin friction can be determined with an indirect method, using the following tables (Table 3, Table 4):</div><div style="text-align: justify;"><br />
</div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhYxBwIbM4NyJ3hBvzxnd_A4dhHbB9wpDOTvn04_6DotpTQ77S08RRp99DPxK0KPUabsm3QbM-EdlGt_1V6j0BbHDFOGr4Ccce7stufGoJm-6ix-GvjQSSK57Iw9ygg0QWOV6uoWQF29J8o/s1600-h/Untitled-2.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhYxBwIbM4NyJ3hBvzxnd_A4dhHbB9wpDOTvn04_6DotpTQ77S08RRp99DPxK0KPUabsm3QbM-EdlGt_1V6j0BbHDFOGr4Ccce7stufGoJm-6ix-GvjQSSK57Iw9ygg0QWOV6uoWQF29J8o/s400/Untitled-2.jpg" /></a><br />
</div><div style="text-align: justify;"><br />
</div>Similarly to the non-cohesive case average c u is determined between the pile tip and depth of three times the pile diameter under the tip.<br />
<br />
<div style="text-align: justify;">So the unit base and shaft resistance are calculated using the undrained shear strength (cu) of cohesive soils. There are numerous methods to predict c u based on CPT values, but the method used for this purpose has a great influence on the estimated pile capacity. So the final predicted pile capacity may be different using<br />
different methods for undrained shear strength prediction.<br />
</div><div style="text-align: justify;"><br />
</div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh2TDQbjkNN0eh0mWOM2WdF6ZB5TKbb2mnvZ7kPCzYJCccgIVh6VuY7Il8V7bkyDddPAU42v8CeiACNkRGihcECwSjH81PBOn87c55FYOGQIju4ocMLGcK-_EWeQGs-VcaoaGq_Nk7CGha8/s1600-h/Untitled-2.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh2TDQbjkNN0eh0mWOM2WdF6ZB5TKbb2mnvZ7kPCzYJCccgIVh6VuY7Il8V7bkyDddPAU42v8CeiACNkRGihcECwSjH81PBOn87c55FYOGQIju4ocMLGcK-_EWeQGs-VcaoaGq_Nk7CGha8/s400/Untitled-2.jpg" /></a><br />
</div><div style="text-align: justify;"><br />
</div><div style="text-align: center;">Bustamante and Giasenelli (1982) Method<br />
</div><div style="text-align: center;"><br />
</div><div style="text-align: left;">In this case the unit base and shaft resistances of a pile are calculated directly from the cone resistance (qc) using the following equation:<br />
</div><div style="text-align: left;"><br />
</div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjIDfcAQo27ExZHMO9JlpDfhSfVJMuJe2dR50o90d3u5I9V7GFO69kZw6E-koO1Kzxo_tbddwcF8fXCtTU1dKW7WPM99IOSGdj-ZIUB17btDu3k-JFVDhiXTRrUth1E_N-sjLbmGT_Zfspi/s1600-h/Untitled-2.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjIDfcAQo27ExZHMO9JlpDfhSfVJMuJe2dR50o90d3u5I9V7GFO69kZw6E-koO1Kzxo_tbddwcF8fXCtTU1dKW7WPM99IOSGdj-ZIUB17btDu3k-JFVDhiXTRrUth1E_N-sjLbmGT_Zfspi/s200/Untitled-2.jpg" /></a><br />
</div><div style="text-align: left;"><br />
</div><b>where:</b><br />
<br />
<br />
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjb2PDoBF8PLPRchrz0vWfoKN1ZWO5XCC9WgBFsSRyxB5iuLxeel9WPGEsX3UL2cI7jznTVlE1z96LyTDOmsg9U1lGIuY7zV7FQ2Lt0H0Fr5pco2vUdotVQxDLh8_yQul0lU_8x-45PYvpc/s1600-h/Untitled-2.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjb2PDoBF8PLPRchrz0vWfoKN1ZWO5XCC9WgBFsSRyxB5iuLxeel9WPGEsX3UL2cI7jznTVlE1z96LyTDOmsg9U1lGIuY7zV7FQ2Lt0H0Fr5pco2vUdotVQxDLh8_yQul0lU_8x-45PYvpc/s400/Untitled-2.jpg" /></a><br />
</div><br />
<div style="text-align: center;"><b>EUROCODE-7-3 method</b><br />
</div><div style="text-align: center;"><br />
</div><div style="text-align: left;">In this method the maximum unit base and shaft resistance can be derived form the following equations:<br />
</div><div style="text-align: left;"><br />
</div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjto-VAmwNk0t_AsDdGUqt8fhtohd8_q2UEdcR6OGcnUlSNd-mKmi3_BX9EIvw80T0VQNzKGq4NPUXpJHAiEnxAfCD2ZrtSbMbIaMYLXNC84K4LGBlpBEQbawXYVea6Q_0dO08spfwT8F8l/s1600-h/Untitled-2.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjto-VAmwNk0t_AsDdGUqt8fhtohd8_q2UEdcR6OGcnUlSNd-mKmi3_BX9EIvw80T0VQNzKGq4NPUXpJHAiEnxAfCD2ZrtSbMbIaMYLXNC84K4LGBlpBEQbawXYVea6Q_0dO08spfwT8F8l/s320/Untitled-2.jpg" /></a><br />
</div><div style="text-align: left;"><b>where :</b><br />
</div><div style="text-align: left;"><br />
</div><div style="text-align: left;"><b>qc,I, mean</b> : is the mean of the qc,I values over the depth running from the pile base level to a level (critical depth) which is at least 0.7 times and at most 4 times the pile base diameter deeper. (Critical depth: where the calculated value of pmax, base becomes a minimum)<br />
</div><div style="text-align: left;"><br />
</div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiUG03t63PF6Q6M7-eYnAgzI9mm8Nb2yquzBbYxoMe_crauLDldoC1zQ_ITNwbXaSrbZtilVzsNcvu4PVO0LinqFc3hh4JlAwF01J2jK1vImePVsKfTIhAUXrQM9_maN4eb0ivSEtpTDwhv/s1600-h/Untitled-2.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiUG03t63PF6Q6M7-eYnAgzI9mm8Nb2yquzBbYxoMe_crauLDldoC1zQ_ITNwbXaSrbZtilVzsNcvu4PVO0LinqFc3hh4JlAwF01J2jK1vImePVsKfTIhAUXrQM9_maN4eb0ivSEtpTDwhv/s200/Untitled-2.jpg" /></a><br />
</div><div style="text-align: left;"><br />
</div><div style="text-align: left;"><b>qc,II, mean</b> : is the mean of the lowest qc,II values over the depth going upwards from the critical depth to the pile base<br />
</div><div style="text-align: left;"><br />
</div><div class="separator" style="clear: both; text-align: center;"><br />
</div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiTT6hGZ8ceMkh3wqBZbssDyolQuhlp67GS2JZ-ywWvFqXH4KNnnIzKfNBMopTIytrk8WOTN-d6aU3IksNksYjrj3uRHnhKOwpV1vMZd98juI9bYBuwRx_HUWo-XdKc6-Qg9P3DlYvMzTIZ/s1600-h/Untitled-2.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiTT6hGZ8ceMkh3wqBZbssDyolQuhlp67GS2JZ-ywWvFqXH4KNnnIzKfNBMopTIytrk8WOTN-d6aU3IksNksYjrj3uRHnhKOwpV1vMZd98juI9bYBuwRx_HUWo-XdKc6-Qg9P3DlYvMzTIZ/s200/Untitled-2.jpg" /></a><br />
</div><div style="text-align: left;"><br />
</div><div style="text-align: left;"><b>qc,III, mean</b> : is themean value of the qc,III values over a depth interval running from the pile base level to a level of 8 times the pile base diameter higher. This procedure starts with the lowest qc,II value used for computation of qc,II, mean.<br />
</div><div style="text-align: left;"><br />
</div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjJNTiUJFl1s7Lc93RrMFNYJhlKH9OzWZRflu4GkFyo4oMx89B3rJvCCxNkCh74OFjYkhaFzAPkC-2yEdbv6vtP4JBM9iUruwsueWxnply41IxP8trebvloGdW1YFy-oMIML0If4HOmGt8m/s1600-h/Untitled-2.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjJNTiUJFl1s7Lc93RrMFNYJhlKH9OzWZRflu4GkFyo4oMx89B3rJvCCxNkCh74OFjYkhaFzAPkC-2yEdbv6vtP4JBM9iUruwsueWxnply41IxP8trebvloGdW1YFy-oMIML0If4HOmGt8m/s200/Untitled-2.jpg" /></a><br />
</div><div style="text-align: left;"><br />
</div><div style="text-align: left;"><b>qc,z</b> is qc at depth z<br />
<b>αp</b> is the pile class factor<br />
<b>αs</b> is a factor depending on the pile class and soil conditions (Table6).<br />
</div><div style="text-align: left;"><br />
</div><div style="text-align: center;"><br />
</div><div style="text-align: center;"><b>ERTC3 Method</b><br />
</div><div style="text-align: center;"><br />
</div><div style="text-align: left;">This method has the same process for calculation of unit base resistance as the EC 7-3 method, but the determination of the shaft resistance is modified. It can be calculated with the same process, but αs values are different (Table 7).<br />
</div><div style="text-align: left;"><br />
</div><div style="text-align: center;"><b>A. MAHLER</b><br />
</div><div style="text-align: center;"><br />
</div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgJQPQSFb5am7xtXcQxWop6EqVZZfsZZ4sBpoc-iw3n6zKzt90Ixh0ECLOqoAo2kPGq2F4CdnbSDPPIetuLLgy5uip5ARL9Xw5XymDWlMnZxhJ566G8HifBeOthFBpM4dGUxgYT17tU1IUH/s1600-h/Untitled-2.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgJQPQSFb5am7xtXcQxWop6EqVZZfsZZ4sBpoc-iw3n6zKzt90Ixh0ECLOqoAo2kPGq2F4CdnbSDPPIetuLLgy5uip5ARL9Xw5XymDWlMnZxhJ566G8HifBeOthFBpM4dGUxgYT17tU1IUH/s640/Untitled-2.jpg" /></a><br />
</div><div style="text-align: center;"><br />
</div><div style="text-align: center;"><i><b>Fig. 1. DIN 4014 method</b></i><br />
</div><div style="text-align: center;"><br />
</div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjhsjmoGrZs6OZv-gj9kp9Ii4OCDvoxyGW2Sz-7m_Vfh-OPxJylJEeVTfb-OyCDS9L2GCwPGmonx1_fDdD5MVjRLFeFkWxUBdM_GGuuEvfHtXvJzLKesl8TCZ2AwLHRwtl_OQIVbzToKARK/s1600-h/Untitled-2.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjhsjmoGrZs6OZv-gj9kp9Ii4OCDvoxyGW2Sz-7m_Vfh-OPxJylJEeVTfb-OyCDS9L2GCwPGmonx1_fDdD5MVjRLFeFkWxUBdM_GGuuEvfHtXvJzLKesl8TCZ2AwLHRwtl_OQIVbzToKARK/s320/Untitled-2.jpg" /></a><br />
</div><div style="text-align: center;"><i><b>Fig. 2. LCPC method</b></i><br />
</div><div style="text-align: center;"><br />
</div><div style="text-align: left;"><b>Reliability of the Prediction Methods</b><br />
</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;">In the following figures the results of the pile capacity predictions are shown. In each figure the predicted pile capacity values are plotted against the results of pile load tests (measured pile capacity). The continuous lines represent the perfect prediction ‘zone’.<br />
</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"><b>Fig. 1</b> shows the results of the DIN 4014 method. As it was mentioned earlier it is an indirect method in case of cohesive soils, so the prediction method of undrained shear strength (cu ) has a serious effect on the calculated pile capacity. So it is obvious that the reliability of this method is varying with various c u prediction<br />
methods.<br />
<br />
</div><div style="text-align: justify;"><b>LCPC (BUSTAMANTE and GIASENELLI, 1982)</b> method provides a direct calculation process using solely the measured cone tip resistance (q c) values. The results of this method are shown in Fig. 2. By comparing the two figures we can say that this process gives similarly accurate pile capacity values. Fig. 3 shows the results of the EUROCODE 7-3 method. Among the investigated methods this one has the most complicated process for estimation of unit base resistance of a pile. This calculation process results in very accurate results, but the prediction of unit skin friction is less accurate in some cases. As it can be seen in Fig. 3 in these particular cases the pile capacities are extremely overestimated. These piles were of large diameter, long piles in stiff clays of high plasticity and in each case the skin friction of the piles were overestimated.<br />
<br />
</div><div style="text-align: justify;"><b>The ERTC 3</b> method has the same process for determination of unit base resistance, but the calculation process of unit skin friction is modified. In Fig.4 the results of this prediction method are shown. We can see that this method gives reliable results even in cases in which the pile capacities were extremely overestimated by <b>EUROCODE 7-3 method.</b><br />
</div><div style="text-align: justify;"><br />
</div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEio-aDHD04mynz3FX3KifwFY7SX7TENFtSLviI1vlwJWoJk08ejPMRp7ZO0M9CZmR31tiGKK5LhfagQ8wQZ71B9e4R1FE28JhtWIatBiFIQKrU9yd2T91EdAGVT3w1VOM9iZvt8MDSkoWj3/s1600-h/Untitled-2.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEio-aDHD04mynz3FX3KifwFY7SX7TENFtSLviI1vlwJWoJk08ejPMRp7ZO0M9CZmR31tiGKK5LhfagQ8wQZ71B9e4R1FE28JhtWIatBiFIQKrU9yd2T91EdAGVT3w1VOM9iZvt8MDSkoWj3/s400/Untitled-2.jpg" /></a><br />
</div><div style="text-align: center;"><b>Fig. 4. ERTC 3 method</b><br />
</div><div style="text-align: center;"><br />
</div><div style="text-align: left;"><br />
</div><div style="text-align: left;"><b>Summary and Conclusion</b><br />
</div><div style="text-align: left;"><br />
</div><div style="text-align: left;">Four pile capacity methods were evaluated using CPT data for thirteen full scale axial pile load tests. The test piles were CFA piles with various geometry and were measured in various soil conditions. DIN 4014, LCPC, EUROCODE 7-3 and ERTC 3 methods were used for pile capacity predictions.<br />
</div><div style="text-align: left;"><br />
</div><div style="text-align: left;">Although the number of performed tests is not enough for statistical analysis, the results of performed tests are summarized in the following table (Table8):<br />
</div><div style="text-align: left;"><br />
</div><div style="text-align: left;">In case of the <b>EUROCODE 7-3 </b>method the standard deviation and average estimated value are higher than the respective values of othermethods. Nevertheless these differences are caused by the overestimation of pile capacities of some piles. Without these results the EUROCODE 7-3 method gives similarly reliable results for pile capacity.<br />
</div><div style="text-align: left;"><br />
</div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhlTKUbSO8jU1_Xhx3chHjModHO5TWfDUG8JRS0-xl5TUK0lsHW_rauX7BeC2mE0djrYqALdRExD69RA4Rn171enzGJPNc0VeL8wpZIW9jw3XuT5xxd28XEhQVJGbOowDzv4O_tS0PZHmBR/s1600-h/Untitled-2.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhlTKUbSO8jU1_Xhx3chHjModHO5TWfDUG8JRS0-xl5TUK0lsHW_rauX7BeC2mE0djrYqALdRExD69RA4Rn171enzGJPNc0VeL8wpZIW9jw3XuT5xxd28XEhQVJGbOowDzv4O_tS0PZHmBR/s320/Untitled-2.jpg" /></a><br />
</div><div style="text-align: center;"><b>Table 8. Results of performed tests</b><br />
</div><div style="text-align: center;"><br />
</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;">It is necessary to note that the pile capacities were generally overestimated. To decide whether it is caused by the differing soil conditions or by differences in the pile installation process requires further studies. Nevertheless it is clear that these methods represent a useful tool in geotechnical design.<br />
</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"><b>References</b><br />
</div><div style="text-align: justify;"><br />
</div><ol style="text-align: justify;"><li>BUSTAMANTE,M.–GIANESELLI, L., Pile Bearing Capacity Prediction by Means of Static Penetrometer CPT. Proceedings of the 2nd European Symposium on Penetration Testing, ESOPT-II, Amsterdam, 2 (1982), pp. 493–500.</li>
<li>DE COCK,F.–LEGRAND, C. ed. Design of Axially Loaded Piles, European Practice, 1997.</li>
<li>DE COCK,F.–LEGRAND,C.–LEHANE,B.ed. Survey Report on Design Methods for Axially Loaded Piles, European Practice, 1999.</li>
<li>EUROCODE 7: Geotechnical Design – Part 3: Design Assisted by Fieldtesting; European Committee for Standardization, 1999.</li>
<li>DIN 4014 Bohrpfähle – Herstellung, Bemessung und Tragverhalten; Deutsche Institut für Normen, 1990.<br />
</li>
</ol><div style="text-align: left;"><br />
</div><div style="text-align: right;"><span style="font-size: x-small;">Source : PERIODICA POLYTECHNICA SER. CIV. ENG. VOL. 47, NO. 2, PP. 189–197 (2003)</span><br />
</div>mayaisjakahttp://www.blogger.com/profile/11820472336428156095noreply@blogger.com2tag:blogger.com,1999:blog-581689683275924296.post-88712205822397272262010-01-17T23:07:00.000-08:002010-01-17T23:19:54.771-08:00NOTES on the CONE PENETROMETER TEST<b>Introduction</b><br />
<div style="text-align: justify;"><br />
</div><div style="text-align: justify;">The standardized cone-penetrometer test (CPT) involves pushing a 1.41-inch diameter 55o to 60o cone (Figs. 1 thru 3) through the underlying ground at a rate of 1 to 2 cm/sec. CPT soundings can be very effective in site characterization, especially sites with discrete stratigraphic horizons or discontinuous lenses. Cone penetrometer testing, or CPT (ASTM D-3441, adopted in 1974) is a valuable method of assessing subsurface stratigraphy associated with soft materials, discontinuous lenses, organic materials (peat), potentially liquefiable materials (silt, sands and granule gravel) and landslides.<br />
</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;">Cone rigs can usually penetrate normally consolidated soils and colluvium, but have also been employed to characterize d weathered Quaternary and Tertiary-age strata. Cemented or unweathered horizons, such as sandstone, conglomerate or massive volcanic rock can impede advancement of the probe, but the author has always been able to advance CPT cones in materials of Tertiary-age sedimentary rocks. The cone is able to delineate even the smallest (0.64 mm/1/4-inch thick) low strength horizons, easily missed in conventional (small-diameter) sampling programs. Some examples of CPT electronic logs are attached, along with hand-drawn lithologic interpretations. <br />
</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;">Most of the commercially-available CPT rigs operate electronic friction cone and piezocone penetrometers, whose testing procedures are outlined in ASTM D-5778, adopted in 1995. These devices produce a computerized log of tip and sleeve resistance, the ratio between the two, induced pore pressure just behind the cone tip, pore pressure ratio (change in pore pressure divided by measured pressure) and lithologic interpretation of each 2 cm interval are continuously logged and printed out.<br />
</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"><b>Tip Resistance</b><br />
</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;">The tip resistance is measured by load cells located just behind the tapered cone (Figure 4). The tip resistance is theoretically related to undrained shear strength of a saturated cohesive material, while the sleeve friction is theoretically related to the friction of the horizon being penetrated (Robinson and Campanella, 1986, Guidelines for Use and Interpretation of the Electric Cone Penetration Test, 3rd Ed.: Hogentogler & Co., Gaithersburg, MD, 196 p.). The tapered cone head forces failure of the soil about 15 inches ahead of the tip and the resistance is measured with an embedded load cell in tons/ft2 (tsf). <b></b><br />
</div><div style="text-align: justify;"><b><br />
</b><br />
</div><div style="text-align: justify;"><b>Local Friction</b><br />
</div><div style="text-align: justify;"><b><br />
</b><br />
</div><div style="text-align: justify;">The local friction is measured by tension load cells embedded in the sleeve for a distance of 4 inches behind the tip (Figure 4). They measure the average skin friction as the probes advanced through the soil. If cohesive soils are partially saturated, they may exert appreciable skin friction, negating the interpretive program. <b> </b><br />
</div><div style="text-align: justify;"><b><br />
</b><br />
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</div><div style="text-align: justify;"><b>Figure 1 (left)</b> – Cone tip exposed beneath truck, just before being advanced into the ground at a rate between 1 and 2 cm/sec. The cone has an area of either 10 or 15 cm and is typically advanced in 1 m increments because the rods are of that length. <br />
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<b>Figure 2 (right)</b> – Hogentogler CPT rig operated by Ertec in Long Beach, CA. Cone rigs weigh about 18 tons, so are capable of exerting considerable normal force on the advancing rod. The cone tip includes a plumb meter to warn of out-of-vertical penetration. <br />
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</div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiTxqsUvWx-22SjvddkG4FRY0d7EjJpvLXS0a7qRnRJtm5PTOeGWMLV-R0s6i6PMND9u56DGkffls7A7km3WgRGW4B5TKDzYDi3yaxvcdDM8H5F1Oo-Fggv-tCoDYCcLjEdPRcwkBi55tf9/s1600-h/Untitled-2.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiTxqsUvWx-22SjvddkG4FRY0d7EjJpvLXS0a7qRnRJtm5PTOeGWMLV-R0s6i6PMND9u56DGkffls7A7km3WgRGW4B5TKDzYDi3yaxvcdDM8H5F1Oo-Fggv-tCoDYCcLjEdPRcwkBi55tf9/s400/Untitled-2.jpg" /></a><br />
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</div>Figure 3 – Manufacturing and operating tolerances of cones, taken from ASTM D5778.<br />
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<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj7vcNOQpbhGeRZdkTlwoLMYcsf8eMLqd3UxWpvRirB0YAU0v9B_DZWi7fQ9nWO0bdjZ-Q5D5_5Eu37wWSuXiDjnteF6d6TvpX32U4Sz5PvglPaECWyUUQgkb-9o9VSCBJtb7yIHVtA76VR/s1600-h/Untitled-3.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj7vcNOQpbhGeRZdkTlwoLMYcsf8eMLqd3UxWpvRirB0YAU0v9B_DZWi7fQ9nWO0bdjZ-Q5D5_5Eu37wWSuXiDjnteF6d6TvpX32U4Sz5PvglPaECWyUUQgkb-9o9VSCBJtb7yIHVtA76VR/s400/Untitled-3.jpg" width="359" /></a><br />
</div>Figure 4 – Schematic section through an electric friction-cone penetrometer tip, taken from ASTM D3441.<br />
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<b>Friction ratio</b><br />
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<div style="text-align: justify;">The friction ratio is given in percent. It is the ratio of skin friction divided by the tip resistance (both in tsf). It is used to classify the soil, by its behavior, or reaction to the cone being forced through the soil. High ratios generally indicate clayey materials (high c, low Ø) while lower ratios are typical of sandy materials (or dry desiccated clays). Typical skin friction to tip friction ratios are 1 % to 10%. The ratio seldom, if ever, exceeds 15%. Sands are generally identified by exhibiting a ratio < 1%. <br />
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<div style="text-align: justify;">Piezocones also measure insitu pore pressure (in psi), in either dynamic (while advancing the cone) or static (holding the cone stationary) modes. Piezocones employ a porous plastic insert just behind the tapered head that is made of hydrophilic polypropylene, with a nominal particle size of 120 microns (Figure 5). The piezocell must be saturated with glycerin prior to its employment. The filter permeability is about 0.01 cm/sec (1 x 10-2 cm/sec).<br />
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<div style="text-align: justify;">When using the cone to penetrate dense layers, such as cemented siltstone, sandstone or conglomerate, the piezo filter element can become compressed, thereby inducing high positive pore pressures. But, the plastic filters do not exhibit this tendency, though they do become brittle with time and may need to be replaced periodically. In stiff over-consolidated clays the pore pressure gradient around the cone may be quite <br />
high. This pore pressure gradient often results in dissipations recorded behind the CPT tip that initially increase before decreasing to the equilibrium value. <br />
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<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhSk_yGzq_3-2v8wv51CkinxiR6qN71c1GasF6xcUBrePIbdZVM2FtVL532JGoqsLWcn0kqO92yp_Dsbkd7n70M60ox1II4x_SusfCuBwZqlVEosg3nYnIJVkjFj3F2qQG4j2jGvB8A0I3A/s1600-h/Untitled-1.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhSk_yGzq_3-2v8wv51CkinxiR6qN71c1GasF6xcUBrePIbdZVM2FtVL532JGoqsLWcn0kqO92yp_Dsbkd7n70M60ox1II4x_SusfCuBwZqlVEosg3nYnIJVkjFj3F2qQG4j2jGvB8A0I3A/s640/Untitled-1.jpg" /></a><br />
</div>Figure 5- Schematic section through a piezocone head, showing the piezo-element and friction sleeve.Taken from ASTM D5778.<br />
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<b>Differential Pore Pressure</b><br />
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<div style="text-align: justify;"><b>The Differential Pore Pressure Ratio</b> is used to aid in soil classification according to the <b>Unified Soil Classification System (USCS)</b>. When the cone penetrates dense materials like sand, the sand dilates and the pore pressure drops. In clayey materials high pore pressures may be induced by the driving of the cone head. If transient pore pressures are being recorded that seem non-hydrostatic, most experienced operators will ask that the penetration be halted and allowed at least 5 minutes to equilibrate, so a quasi-static pore pressure reading can be recorded. Sometimes equilibration can take 10 to 30 minutes, depending on the soil. In practice experienced operators try to stop the advance and take pore pressure measurements in recognized aquifers and just above or adjacent to indicated aquacludes.<br />
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</div><div style="text-align: justify;"><b>Temperature sensor </b><br />
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</div><div style="text-align: justify;">One great advantage of the electric cone is the temperature sensor. This has been found to be very useful in assessing the precise position of the zone, or zones, of saturation, which is of great import in slope stability and consolidation studies. A temperature shift of about 6o F is common at the groundwater interface, even perched horizons within landslides. <br />
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</div><div style="text-align: justify;"><b>Corrected Logs</b><br />
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</div><div style="text-align: justify;">Most CPT rigs are equipped with one or several automated interpretation programs, which classify 1 cm horizons according to the Unified Soil Classification System. The most widely employed routine has been that originally developed by Robinson and Campanella, available from Hogentogler & Co., of Gaithersburg, MD or from the Natural Sciences and Engineering Research Council of Canada. An alternative interpretation program was developed by Dr. Richard Olsen (available through www.liquefaction.com). <br />
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The interpretation programs evaluates all of the measured properties and classifies the horizon according to its behavior (in lieu of petrology). For instance, when classifying a clayey material the interpretive programs consider undrained shear strength, tip resistance and differential pore pressure. A high differential pore pressure is assumed diagnostic of more clayey materials.<br />
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</div><div style="text-align: justify;"><b>Importance of “ground-truthing”</b><br />
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</div><div style="text-align: justify;">Like geophysical techniques, CPT soundings are most meaningful when “ground-truthed” with established lithologic horizons. The easiest method to “ground truthing” CPT data is to advance a sounding next to a bucket auger or conventional boring, from which subsurface samples are collected. In this way the electronic “signature” of the sounding can be compared with the various lithologies already identified in the substory. This comparison can prove especially valuable in identifying potentially liquefiable materials and old landslide slip surfaces. Once the CPT sounding is “ground-truthed”, the rig can traverse the job site, commonly advancing 10 or 12 soundings in a single day. This allows for an expanded data set, which allows superior three-dimensional characterization of the site under evaluation, and allows construction of reliable geologic cross sections through the area.<br />
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</div><div style="text-align: justify;"><b>Notes of Caution </b><br />
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</div><div style="text-align: justify;">Some notes of caution are advised when applying the CPT method to evaluating discrete low-strength horizons or partings, such as landslide slip surfaces. The 60o tip of the cone forces a passive failure of the ground in front of the advancing tip. The instrumented tip senses soil resistance about 21cm (8.4 in) ahead of the advancing tip. <br />
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</div><div style="text-align: justify;">This means that the tip resistance reported as “undrained shear strength” is actually an average value, taken over the zone within 21 cm of the cone tip. If the tip penetrates low strength horizons less than 21 cm thick, such as a landslide slip surface, the tip resistance reported on the CPT log may be much higher than actually exists on the discrete plane of slippage, which maybe only a fraction of an inch thick.<br />
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</div><div style="text-align: justify;">Another problem with the CPT method is that cone soundings advanced through desiccated clay will often be interpreted as sand or silt mixtures (by the computerized lithologic interpretation routine) because of recorded sleeve friction. The opposite problem occurs when reporting Standard Penetration Test (SPT) blow counts after advancing drive samples through clayey horizons! The SPT test is only intended for granular materials, and blow counts in such materials must be regarded with some degree of skepticism as they may shift dramatically upon later absorption of moisture. <br />
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</div><div style="text-align: justify;"><b>Sample CPT logs</b><br />
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</div><div style="text-align: justify;">The attached logs are representative of the features common to electronic friction cones. They include raw data sensed by the cone as it is pushed through the ground. This data includes: Friction Ratio, Local Friction, Tip Resistance, Pore Pressure, Differential Pore Pressure Ratio and an interpreted lithologic profile (often printed out on a separate sheet, depending on which interpretation program is being utilized). <br />
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