1、Designation: D5321/D5321M 17Standard Test Method forDetermining the Shear Strength of Soil-Geosynthetic andGeosynthetic-Geosynthetic Interfaces by Direct Shear1This standard is issued under the fixed designation D5321/D5321M; the number immediately following the designation indicates theyear of orig
2、inal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of lastreapproval. A superscript 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, withthe exception of geosynthetic clay liners (GCLs) which areaddressed in Test Method D6243/D6243M.1.3 The test method is not suited for the development of
5、exact stress-strain relationships for the test specimen due to thenonuniform distribution of shearing forces and displacement.1.4 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equivalents; therefore
6、, eachsystem shall be used independently of the other. Combiningvalues from the two systems may result in nonconformancewith the standard.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 standard to est
7、ablish appropriate safety andhealth practices and determine the applicability of regulatorylimitations prior to use.1.6 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment
8、 of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D653 Terminology Relating to Soil, Rock, and ContainedFluidsD698 Test Methods for Laboratory Compaction Character-isti
9、cs of Soil Using Standard Effort (12,400 ft-lbf/ft3(600kN-m/m3)D1557 Test Methods for Laboratory Compaction Character-istics of Soil Using Modified Effort (56,000 ft-lbf/ft3(2,700 kN-m/m3)D2435/D2435M Test Methods for One-Dimensional Con-solidation Properties of Soils Using Incremental LoadingD2487
10、Practice for Classification of Soils for EngineeringPurposes (Unified Soil Classification System)D3080/D3080M Test Method for Direct Shear Test of SoilsUnder Consolidated Drained ConditionsD3740 Practice for Minimum Requirements for AgenciesEngaged in Testing and/or Inspection of Soil and Rock asUse
11、d in Engineering Design and ConstructionD4354 Practice for Sampling of Geosynthetics and RolledErosion Control Products (RECPs) for TestingD4439 Terminology for GeosyntheticsD6243/D6243M Test Method for Determining the Internaland Interface Shear Strength of Geosynthetic Clay Linerby the Direct Shea
12、r Method3. Terminology3.1 Definitions:3.1.1 For definitions of terms relating to soil and rock, referto Terminology D653. For definitions of terms relating togeosynthetics, refer to Terminology D4439.3.2 Definitions of Terms Specific to This Standard:3.2.1 adhesion, ca,nthe y-intercept of the Mohr-C
13、oulombstrength envelope.3.2.2 atmosphere for testing geosynthetics, nair main-tained at a relative humidity between 50 and 70 % and atemperature of 21 6 2 C 70 6 4 F.1This test method is under the jurisdiction of ASTM Committee D35 onGeosynthetics and is the direct responsibility of Subcommittee D35
14、.01 on Mechani-cal Properties.Current edition approved June 1, 2017. Published June 2017. Originallyapproved in 1992. Last previous edition approved in 2014 as D5321/D5321M 14.DOI: 10.1520/D5321_D5321M-17.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer S
15、ervice at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed i
16、n accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.13.2.3 Mohr-Coulomb fricti
17、on angle, ,n(angle of frictionof a material or between two materials, ) the angle defined bythe least-squares, “best-fit” straight line through a definedsection of the shear strength-normal stress failure envelope; thecomponent of the shear strength indicated by the term ,inCoulombs equation, =ca+ n
18、* tan ( ) (see 12.6).3.2.3.1 DiscussionThe end user is cautioned that someorganizations (for example, FHWA,AASHTO, along with stateagencies who use these documents) are currently using theGreek letter, Delta (), to designate wall-backfill interfacefriction angle and the Greek letter, Rho (), to desi
19、gnate theinterface friction angle between geosynthetics and soil.3,43.2.4 Mohr-Coulomb shear strength envelope, nthe leastsquares, “best fit” straight line through a defined section of theshear strength-normal stress failure envelope described by theequation, =ca+ n* tan ( ) (see 12.6). The envelope
20、 can bedescribed for any chosen shear failure mode (example, peak orpost-peak).3.2.5 secant friction angle, sec,n(angle of friction of amaterial or between two materials, ) the angle defined by aline drawn from the origin to a data point on the shearstrength-normal stress failure envelope. Intended
21、to be usedonly for the normal stress on the shearing plane for which it isdefined.3.2.6 shear strength, ,nthe shear force on a given failureplane. In the direct shear test it is always stated in relation tothe normal stress acting on the failure plane. Two differenttypes of shear strengths are often
22、 estimated and used instandard practice:3.2.6.1 peak shear strengththe largest value of shearresistance experienced during the test under a given normalstress.3.2.6.2 post-peak shear strengththe minimum, or steady-state value of shear resistance that occurs after the peak shearstrength is experience
23、d.3.2.6.3 DiscussionThe end user is cautioned that thereported value of post-peak shear strength (regardless howdefined) is not necessarily the residual shear strength. In someinstances, a post-peak shear strength may not be defined beforethe limit of horizontal displacement is reached.3.2.7 shear s
24、trength envelope, ncurvi-linear line on theshear stress-normal stress plot representing the combination ofshear and normal stresses that define a selected shear failuremode (for example, peak and post-peak).4. Summary of Test Method4.1 The shear resistance between a geosynthetic and a soil,or other
25、material selected by the user, is determined by placingthe geosynthetic and one or more contact surfaces, such as soil,within a direct shear box. A constant normal stress represen-tative of design stresses is applied to the specimen, and atangential (shear) force is applied to the apparatus so that
26、onesection of the box moves in relation to the other section. Theshear force is recorded as a function of the shear displacementof the moving section of the shear box.4.2 To define a Mohr-Coulomb shear strength envelope, it isrecommended that a minimum of three test points be per-formed at different
27、 normal stresses, selected by the user, tomodel appropriate field conditions. However, there may beinstances where fewer test points are desired (see Note 1). Thepeak shear stresses, or shear stresses at some post-peakdisplacement, or both, are plotted against the applied normalstresses used for tes
28、ting. The test data are generally representedby a best-fit straight line through the peak strength valueswhose slope is the Mohr-Coulomb friction angle for peakstrength between the two materials where the shearing oc-curred. The y-intercept of the straight line is the adhesionintercept.Astraight lin
29、e fit for shear stresses at some post-peakdisplacement is the post-peak interface strength between thetwo materials where the shearing occurred.NOTE 1There may be some investigative cases where only a singletest point is desired. If the field design conditions will experience a rangeof normal stress
30、es, it is standard industry practice to bracket the normalstress range with tests on both sides of the range, as it is unconservativeto extrapolate results outside of the normal stress range tested. Whendefining a Mohr-Coulomb shear strength envelope over a range of normalstresses, standard industry
31、 practice is to use a minimum of three testpoints. Attempting to define a single linear Mohr-Coulomb shear strengthenvelope over too large of a normal stress range may prove to beproblematic in many cases because most failure envelopes exhibitsignificant curvature over such a large range, particular
32、ly at low normalstresses on the shearing plane.5. Significance and Use5.1 The procedure described in this test method for deter-mination of the shear resistance of the soil and geosynthetic orgeosynthetic and geosynthetic interface is intended as a per-formance test to provide the user with a set of
33、 design values forthe test conditions examined. The test specimens andconditions, including normal stresses, are generally selected bythe user.5.2 This test method may be used for acceptance testing ofcommercial shipments of geosynthetics, but caution is advisedas outlined in 5.2.1.5.2.1 The shear r
34、esistance can be expressed only in terms ofactual test conditions (see Note 2 and Note 3). The determinedvalue may be a function of the applied normal stress, materialcharacteristics (for example, of the geosynthetic), soilproperties, size of sample, moisture content, drainageconditions, displacemen
35、t rate, magnitude of displacement, andother parameters.NOTE 2In the case of acceptance testing requiring the use of soil, theuser must furnish the soil sample, soil parameters, and direct shear testparameters. The method of test data interpretation for purposes ofacceptance should be mutually agreed
36、 to by the users of this test method.NOTE 3Testing under this test method should be performed bylaboratories qualified in the direct shear testing of soils and meeting therequirements of Practice D3740, especially since the test results maydepend on site-specific and test conditions.3LRFD Bridge Des
37、ign Specifications, 5th Edition,AmericanAssociation of StateHighway and Transportation Officials (AASHTO), Washington, D.C., 2010.4“Mechanically Stabilized Earth Walls and Reinforced Soil Slopes, Design andConstruction Guidelines,”FHWA GEC 011, FHWA NHI-10-024, Vol I, and FHWANHI-10-025, Vol II, U.S
38、. Department of Transportation, Federal Highway Admin-istration (FHWA), Washington, D.C., 2009.D5321/D5321M 1725.2.2 This test method measures the total resistance to shearbetween a geosynthetic and a supporting material (substratum)or a geosynthetic and an overlying material (superstratum).The tota
39、l shear resistance may be a combination of sliding,rolling, and interlocking of material components.5.2.3 This test method does not distinguish between indi-vidual mechanisms, which may be a function of the soil andgeosynthetic used, method of material placement andhydration, normal and shear stress
40、es applied, means used tohold the geosynthetic in place, rate of shear displacement, andother factors. Every effort should be made to identify, asclosely as practicable, the sheared area and failure mode of thespecimen. Care should be taken, including close visual inspec-tion of the specimen after t
41、esting, to ensure that the testingconditions are representative of those being investigated.5.2.4 Information on precision among laboratories is incom-plete. In cases of dispute, comparative tests to determinewhether a statistical bias exists among laboratories may beadvisable.5.3 The test results c
42、an be used in the design of geosyntheticapplications including, but not limited to, the design of linersand caps for landfills, mining heap leach pads, tailingsimpoundments, cutoffs for dams and other hydraulic barriers,geosynthetic-reinforced retaining walls, embankments, andbase courses; in applic
43、ations in which the geosynthetic isplaced on a slope; for determination of geosynthetic overlaprequirements; or in other applications in which sliding mayoccur between soil and a geosynthetic or between two geosyn-thetic materials.5.4 The displacement at which peak strength and post-peakstrength occ
44、urs and the shape of the shear stress versus sheardisplacement curve may differ considerably from one testdevice to another due to differences in specimen mounting,gripping surfaces, and material preparation. The user of resultsfrom this test method is cautioned that results at a specifieddisplaceme
45、nt may not be reproducible across laboratories andthat the relative shear displacement measured in this test atpeak strength may not match relative shear displacement atpeak strength in a field condition.6. Apparatus6.1 Shear DeviceA rigid device to hold the specimensecurely and in such a manner tha
46、t a uniform shear forcewithout torque can be applied to the tested interface. Thedevice consists of both a stationary and moving container, eachof which is capable of containing dry or wet soil and is rigidenough to not distort during shearing of the specimen. Thetraveling container must be placed o
47、n firm bearings and rack toensure that the movement of the container is only in a directionparallel to that of the applied shear force.NOTE 4The position of one of the containers should be adjustable inthe normal direction to compensate for vertical deformation of thesubstrate and geosynthetic.6.1.1
48、 Square or rectangular containers are recommended.They should have a minimum dimension that is the greatest of300 mm 12 in., 15 the d85of the coarser soil used in the test,or a minimum of 5 the maximum opening size (in plan) of thegeosynthetic tested. The depth of each container that containssoil mu
49、st be a minimum of 50 mm 2 in. or 6 the maximumparticle size of the coarser soil tested, whichever is greater.NOTE 5The minimum container dimensions given in 6.1.1 areguidelines based on requirements for testing most combinations ofgeosynthetics and soils. Containers smaller than those specified in 6.1.1can be used if it can be shown that data generated by the smaller devicescontain no bias from scale or edge effects when compared to theminimum-size devices specified in 6.1.1 for specific materials beingtested. The user should conduct c
