1、Designation: D 5321 08Standard Test Method forDetermining the Coefficient of Soil and Geosynthetic orGeosynthetic and Geosynthetic Friction by the Direct ShearMethod1This standard is issued under the fixed designation D 5321; the number immediately following the designation indicates the year oforig
2、inal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers a procedure for determining theshear re
3、sistance of a geosynthetic against soil, or a geosyn-thetic against another geosynthetic, under a constant rate ofdeformation.1.1.1 The test method is intended to indicate the perfor-mance of the selected specimen by attempting to model certainfield conditions. Results obtained from this method may
4、belimited in their applicability to the specific conditions consid-ered in the testing.1.2 The test method is applicable for all geosynthetics.1.3 The test method is not suited for the development ofexact stress-strain relationships for the test specimen due to thenon-uniform distribution of shearin
5、g forces and displacement.1.4 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.5 This standard does not purport to address all the safetyconcerns, if any, associated with its use. It is the responsibilityof the user of this st
6、andard to establish appropriate safety andhealth practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 653 Terminology Relating to Soil, Rock, and ContainedFluidsD 698 Test Methods for Laboratory Compaction Character-istics of So
7、il Using Standard Effort (12 400 ft-lbf/ft3(600kN-m/m3)D 1557 Test Methods for Laboratory Compaction Charac-teristics of Soil Using Modified Effort (56,000 ft-lbf/ft3(2,700 kN-m/m3)D 2435 Test Methods for One-Dimensional ConsolidationProperties of Soils Using Incremental LoadingD 3080 Test Method fo
8、r Direct Shear Test of Soils UnderConsolidated Drained ConditionsD 3740 Practice for Minimum Requirements for AgenciesEngaged in Testing and/or Inspection of Soil and Rock asUsed in Engineering Design and ConstructionD 4354 Practice for Sampling of Geosynthetics for TestingD 4439 Terminology for Geo
9、synthetics3. Terminology3.1 DefinitionsFor definitions of terms relating to soil androck, refer to Terminology D 653. For definitions of termsrelating to geosynthetics, refer to Terminology D 4439.3.2 Descriptions of Terms Specific to This Standard:3.2.1 adhesion,canthe shearing resistance between t
10、woadjacent materials under zero normal stress. Practically, this isdetermined as the y-intercept of a straight line relating thelimiting value of shear stress that resist slippage between twomaterials and the normal stress across the contact surface of thetwo materials. (D 653, D-18)3.2.2 angle of f
11、riction, n(angle of friction between twomaterials) (degrees) the angle whose tangent is the slope of theline relating limiting value of the shear stress that resistsslippage between two solid bodies and the normal stress acrossthe contact surface of the two bodies. Limiting value may be atthe peak s
12、hear stress or at some other failure condition definedby the user of the test results. This is commonly referred to asinterface friction angle. (D 653, D-18)3.2.3 atmosphere for testing geosynthetics, nair main-tained at a relative humidity of 65 6 5 % and temperature of21 6 2C (70 6 4F). (D 4439)3.
13、2.4 coeffcient of friction, nThe slope of the line relatinglimiting value of the shear stress that resists slippage betweentwo materials and the normal stress across the contact surfaceof the two bodies. Limiting value may be at the peak shearstress or at some other failure condition defined by the
14、user.1This test method is under the jurisdiction of ASTM Committee D35 onGeosynthetics and is the direct responsibility of Subcommittee D35.01 on Mechani-cal Properties.Current edition approved July 1, 2008. Published August 2008. Originallyapproved in 1992. Last previous edition approved in 2002 as
15、 D 5321022For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive
16、, PO Box C700, West Conshohocken, PA 19428-2959, United States.(D 653, D-18)3.2.5 direct shear friction test, nfor geosynthetics,aprocedure in which the interface between a geosynthetic andany other surface, under a range of normal stresses specified bythe user, is stressed to failure by the horizon
17、tal movement ofone surface against the other.3.2.6 geosynthetic, na planar synthetic product manufac-tured from polymeric material used with soil, rock, earth, orother geotechnical engineering-related material as an integralpart of a man-made project, structure, or system. (D 4439)3.2.7 limiting val
18、ue, nthe value of shear stress at somecondition, such as the peak value, the ultimate value, or thevalue at some prescribed displacement.4. Summary of Test Method4.1 The shear resistance between a geosynthetic and a soil,or other material selected by the user, is determined by placingthe geosyntheti
19、c and one or more contact surfaces, such as soil,within a direct shear box. A constant normal force representa-tive of design stresses is applied to the specimen, and atangential (shear) force is applied to the apparatus so that onesection of the box moves in relation to the other section. Theshear
20、force is recorded as a function of the horizontal displace-ment of the moving section of the shear box.4.2 The test is performed at a minimum of three differentnormal stresses, selected by the user, to model appropriate fieldconditions. The limiting values of shear stresses are plottedagainst the ap
21、plied normal compressive stresses used fortesting. The test data are generally represented by a best fitstraight line whose slope is the coefficient of friction betweenthe two materials where the shearing occurred. The y-interceptof the straight line is the adhesion.5. Significance and Use5.1 The pr
22、ocedure described in this test method for deter-mination of the coefficient of soil and geosynthetic or geosyn-thetic and geosynthetic friction by the direct shear method isintended as a performance test to provide the user with a set ofdesign values for the test conditions examined. The testspecime
23、ns and conditions, including normal stresses, are gen-erally selected by the user.5.2 This test method may be used for acceptance testing ofcommercial shipments of geosynthetics, but caution is advisedas outlined below.5.2.1 The coefficient of soil and geosynthetic friction can beexpressed only in t
24、erms of the soil used in testing (see Note1and Note 2). The determined value may be a function of theapplied normal stress, geosynthetic material characteristics,soil gradation, soil plasticity, density, moisture content, size ofsample, drainage conditions, displacement rate, magnitude ofdisplacemen
25、t, and other parameters.NOTE 1In the case of acceptance testing requiring the use of soil, theuser must furnish the soil sample, soil parameters, and direct shear testparameters.NOTE 2Testing under this standard should be performed by labora-tories experienced in the direct shear testing of soils an
26、d meeting therequirements of Practice D 37405.2.2 This test method measures the total resistance to shearbetween a geosynthetic and a supporting material (substratum)or a geosynthetic and an overlying material (superstratum).Total sliding resistance may be a combination of sliding,rolling, interlock
27、ing of soil particles and geosynthetic surfaces,and shear strain within the geosynthetic specimen. Shearingresistance may be different on the two faces of a geosyntheticand may vary with direction of shearing relative to orientationof the geosynthetic.5.2.3 The test method does not distinguish betwe
28、en indi-vidual mechanisms, which may be a function of the soil used,method of soil placement, normal and shear stresses applied,rate of horizontal displacement, and other factors. Every effortshould be made to identify and record with a sketch, as closelyas is practicable, the sheared area and failu
29、re mode of thespecimen. Care should be taken, including close visual inspec-tion of the specimen after testing, to ensure that the testingconditions are representative of those being investigated.5.2.4 Information on precision between laboratories is in-complete. In cases of dispute, comparative tes
30、ts to determinewhether a statistical bias exists between laboratories may beadvisable.5.3 The test method produces test data that can be used inthe design of geosyntheic applications, including but notlimited to: the design of geosynthetic-reinforced retainingwalls, embankments, and base courses; in
31、 applications inwhich the geosynthetic is placed on a slope; for determinationof geosynthetic overlap requirements; or in other applicationsin which sliding may occur between soil and a geosynthetic orbetween two geosynthetic materials.6. Apparatus6.1 Shear DeviceA rigid device to hold the specimens
32、ecurely and in such a manner that a shear force without torquecan be applied to the specimen. The device consists of both astationary and moving container, both of which are capable ofcontaining dry or wet soil and are rigid enough to not distortduring shearing of the specimen. The traveling contain
33、er mustbe placed on firm bearings and rack, or other mechanism, toensure that the movement of the container encounters lowfriction and is only in a direction parallel to that of the appliedshear force.NOTE 3The position of one of the containers should be adjustable inthe normal direction to compensa
34、te for deformation of the substrate andgeosynthetic. Thecontainer should also be aligned to minimize anymoment produced by non-colinear forces on the containers.6.1.1 Square or rectangular containers are recommendedand they should have a minimum dimension that is the greaterof 300 mm (12 in.), 15 ti
35、mes the d85of the coarser soil used inthe test, or a minimum of five times the maximum opening size(in plan) of the geosynthetic tested. The depth of each containerthat contains soil must be a minimum of 50 mm (2 in.) or sixtimes the maximum particle size of the coarser soil tested,whichever is grea
36、ter.NOTE 4The minimum container dimensions given in 6.1.1 are guide-lines based on requirements for testing most combinations of geosynthet-ics and soils. Containers smaller than those specified in 6.1.1 can be usedif it can be shown that data generated by the smaller devices contain nobias when com
37、pared to the minimum size devices specified in 6.1.1. Theuser should conduct comparative testing prior to the acceptance of dataproduced on smaller devices. For direct shear testing involving soils,D 5321 082competent geotechnical review is recommended to evaluate the compat-ibility of the minimum a
38、nd smaller direct shear devices.6.2 Normal Stress Loading Device, capable of applying andmaintaining a constant uniform normal stress on the specimenfor the duration of the test. Careful control and accuracy(62 %) of the normal stress is important. Normal stressloading devices include, but are not l
39、imited to, weights,pneumatic or hydraulic bellows, or piston-applied stresses. Forjacking systems, the tilting of loading plates must be limited to2 from the shear direction during shearing. The device mustbe calibrated to determine the normal stress delivered to theshear plane.6.3 Shear Force Loadi
40、ng Device, capable of applying ashearing force to the specimen at a constant rate of displace-ment in a direction parallel to the direction of travel of themoving container. The horizontal force measurement systemmust be calibrated, includng provisions to measure and correctfor the effects of fricti
41、on and tilting of the loading system. Therate of displacement must be controlled to an accuracy of610 % over a displacement range of of at least 6.35mm/min(0.25 in/min) to 0.025 mm/min (0.001 in/min). The systemmust allow constant measurement and readout of the shearforce applied. An electronic load
42、 cell or proving ring arrange-ment is generally used. The shear force loading device shouldbe connected to the test apparatus in such a fashion that thepoint of the force application to the traveling container is in theplane of the shearing interface and remains the same for alltests.NOTE 5The opera
43、ting range for normal and horizontal stresses for adevice must be limited to between 10% and 90% of its calibrated range.If a device is used outside this range, the report shall so state and give adiscussion of the potential effect of uncertainties in measured forces on thereported results.6.4 Displ
44、acement Indicators, for providing readout of thehorizontal shear displacement and, if desired, vertical displace-ment of the specimen during the consolidation or shear phase.Displacement indicatorus such as dial indicators, or linearvariable differential transformers (LVDT), capable of measur-ing a
45、displacement of at least 75 mm (3 in.) for horizontaldisplacement and 25 mm (1 in.) for vertical displacement arerecommended. The sensitivity of displacement indicatorsshould be 0.02 mm (0.001 in.) for measuring horizontaldisplacement.6.5 Geosynthetic Clamping Devices, required for fixinggeosyntheti
46、c specimens to the stationary section or container,the traveling container, or both, during shear. Clamps shall notinterfere with the shearing surfaces within the shear box andmust keep the geosynthetic specimens flat during testing. Flatjaw-like clamping devices are normally sufficient. Texturedsur
47、faces or soil must be used to support the top and/or bottomof the geosynthetic. These surfaces must permit flow of waterinto and out of the test speciment.Work is still in progress todefine the best type or textured surfaces. Selection of the typeof texture surface should be based on the following c
48、riteria:6.5.1 The gripping surface must be able to prevent theoutside surface of the geosynthetic being sheared from slippingto the extent that the geosynthetic fails.6.5.2 The gripping surface must be able to completelytransfer the shear stress through the outside surfaces into thegeosynthetic.6.5.
49、3 The gripping surface must not damage the geosyn-thetic and should not influence the shear strength behavior ofthe geosynthetic.NOTE 6The selection of specimen substrate may influence the testresults. For instance, a test performed using a rigid substrate, such as awood or metal plate, may not simulate field conditions as accurately asthat using a soil substrate. The user should be aware of the influence ofsubstrate on direct shear friction data.Accuracy and reproducibility shouldbe considered when selecting a substrate for testing.6.6 Soil Preparation Equipment
