1、Designation: D6243 13D6243/D6243M 13aStandard Test Method forDetermining the Internal and Interface ShearResistanceStrength of Geosynthetic Clay Liner by the DirectShear Method1This standard is issued under the fixed designation D6243;D6243/D6243M; the number immediately following the designation in
2、dicatesthe year of original 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
3、determining the internal shear resistance of a Geosynthetic Clay Liner (GCL) orthe interface shear resistance between the GCL and an adjacent material under a constant rate of displacement or constantstress.deformation.1.2 This test method is intended to indicate the performance of the selected spec
4、imen by attempting to model certain fieldconditions.1.3 This test method is applicable to all GCLs. Remolded or undisturbed soil samples can be used in the test device. See TestMethod D5321 for non-GCLs.1.4 This test method is not suited for the development of exact stress-strain relationships withi
5、n the test specimen due to thenonuniform distribution of shearing forces and displacement.1.5 The values stated in either SI units or inch-pound units are to be regarded separately as the standard. The values given inparentheses are for information only.stated in each system may not be exact equival
6、ents; therefore, each system shall be usedindependently of the other. Combining values from the two systems may result in non-conformance with the standard.1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user o
7、f this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D653 Terminology Relating to Soil, Rock, and Contained FluidsD698 Test Methods for Laboratory Compaction Characteristi
8、cs of Soil Using Standard Effort (12 400 ft-lbf/ft3 (600 kN-m/m3)D1557 Test Methods for Laboratory Compaction Characteristics of Soil Using Modified Effort (56,000 ft-lbf/ft3 (2,700kN-m/m3)D2435D2435/D2435M Test Methods for One-Dimensional Consolidation Properties of Soils Using Incremental LoadingD
9、2487 Practice for Classification of Soils for Engineering Purposes (Unified Soil Classification System)D3080D3080/D3080M Test Method for Direct Shear Test of Soils Under Consolidated Drained ConditionsD3740 Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil a
10、nd Rock as Used inEngineering Design and ConstructionD4439 Terminology for GeosyntheticsD5321 Test Method for Determining the Shear Strength of Soil-Geosynthetic and Geosynthetic-Geosynthetic Interfaces byDirect ShearD6072D6072/D6072M Practice for Obtaining Samples of Geosynthetic Clay Liners1 This
11、test method is under the jurisdiction of ASTM Committee D35 on Geosynthetics and is the direct responsibility of Subcommittee D35.04 on Geosynthetic ClayLiners.Current edition approved Jan. 1, 2013July 1, 2013. Published February 2012August 2013. Originally approved in 1998. Last previous edition ap
12、proved in 20092013 asD624309.13. DOI: 10.1520/D6243-13.10.1520/D6243_D6243M-13A.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page o
13、n the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that user
14、s consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13. Terminology3.1 Definitions
15、For definitions of terms relating to soil and rock, refer to Terminology D653. For definitions of termtermsrelating to GCLs, refer to Terminology D4439.3.2 Definitions of Terms Specific to This Standard:3.2.1 adhesion, ca, nthe shearing resistance between two unlike materials under zero normal stres
16、s.y-intercept of theMohr-Coulomb strength envelope.3.2.2 angle of friction, n(angle of friction of a material or between two materials, ,) the angle whose tangent is the ratiobetween the limiting value of the shear stress that resists slippage internal to a body or between two solid bodies at rest w
17、ith respectto each other and the normal stress across the contact surface.3.2.2 atmosphere for testing geosynthetics, nair maintained at a relative humidity of between 50 and 70 % and temperatureof 21 6 2C (7070 6 4F).4F.3.2.3 coeffcient of friction, GCL, na constant proportionality factor relating
18、shear to normal stress for a defined failurecondition.manufactured hydraulic barrier consisting of clay bonded to a layer, or layers, of geosynthetic materials.3.2.4 cohesion c, Mohr-Coulomb friction angle, , nshear strength of material, or the interface (angle of friction of a materialor between tw
19、o materials, at zero normal stress; the degrees) the angle defined by the least-squares, “best-fit” straight line througha defined section of the shear strength-normal stress failure envelope; the component of the shear strength indicated by the termc, in Coulombs equationCoulombs equation, = cCa +
20、n * tan ().() (see 12.6).3.2.4.1 DiscussionThe end user is cautioned that some organizations (for example, FHWA, AASHTO along with state agencies who use thesedocuments) are currently using the Greek letter, Delta (), to designate wall-backfill interface friction angle and the Greek letter,Rho (), t
21、o designate the interface friction angle between geosynthetics and soil.3,43.2.5 Mohr-Coulomb shear strength envelope, n(angle of friction between two materials) (degrees) the angle whose tangentis the slope of the line relating limiting value of the shear stress that resists slippage between two so
22、lid bodies and the normal stressacross the contact surface of the two bodies. Limiting value may be at the peak shear stress or at some other failure conditiondefined by the user of the test results. This is commonly referred to as interface friction angle. D6533.2.6 direct shear friction test, seca
23、nt friction angle, sec, nfor GCLs, a procedure in which the internal GCL or the interfacebetween a GCL and any other surface, under a constant normal stress specified by the user, is stressed to failure by the relativemovement of one surface against the other for interface strength and by internal s
24、hear for internal strength.(angle of friction of amaterial or between two materials, ) the angle defined by a line drawn from the origin to a data point on the shear strength-normalstress failure envelope. Intended to be used only for the normal stress on the shearing plane for which it is defined.3
25、.2.7 GCL, na manufactured hydraulic barrier consisting of clay bonded to a layer, or layers, of geosynthetic materials.3.2.8 residual strength, nvalue of shear stress at sufficiently large displacement that shear stress remains constant withcontinued shearing.3.2.7 post-peakshear strength, ,nvalues
26、of shear stress at some displacement beyond the peak shear strength where the shearstress approaches a constant value with continued displacement.the shear force on a given failure plane. In the direct shear test itis always stated in relation to the normal stress acting on the failure plane.Two dif
27、ferent types of shear strengths are often estimatedand used in standard practice:3.2.7.1 peak shear strengththe largest value of shear resistance experienced during the test under a given normal stress.3.2.7.2 post-peak shear strengththe minimum, or steady-state value of shear resistance that occurs
28、 after the peak shearstrength is experienced.3.2.7.3 DiscussionThe end user is cautioned that the reported value of post-peak shear strength (regardless how defined) is not necessarily the residualshear strength. In some instances, a post-peak shear strength may not be defined before the limit of ho
29、rizontal displacement isreached.3.2.8 shear strength envelope, ncurvi-linear line on the shear stress-normal stress plot representing the combination of shearand normal stresses that define a selected shear failure mode (for example, peak and post-peak).3 LRFD Bridge Design Specifications, 5th Editi
30、on, American Association of State Highway and Transportation Officials (AASHTO), Washington, D.C., 2010.4 “Mechanically Stabilized Earth Walls and Reinforced Soil Slopes, Design and Construction Guidelines”, FHWA GEC 011, FHWA-NHI-10024, Vol 1 andFHWA-NHI-10025, Vol II, U.S. Department of Transporta
31、tion, Federal Highway Administration (FHWA), Washington, DC, 2009.D6243/D6243M 13a24. Summary of Test Method4.1 The shear resistance internal to the GCLor between a GCLand adjacent material, or between any GCLcombination selectedby the user, is determined by placing the GCL and one or more contact s
32、urfaces, such as soil, within a direct shear box.Aconstantnormal stress representative of fielddesign stresses is applied to the specimen, and a tangential (shear) force is applied to theapparatus so that one section of the box moves in relation to the other section. The shear force is recorded as a
33、 function of thehorizontal displacement of the moving section of the shear box.4.2 The test is performed for a minimum of three To define a Mohr-Coulomb shear strength envelope, it is recommended thata test points be performed at different normal stresses, selected by the user, to model appropriate
34、field conditions. However, theremay be instances where fewer test points are desired (see Note 1). The peak shear stresses, or shear stresses at some post-peakdisplacement, or both, are plotted against the applied normal stresses used for testing. The test data are generally represented bya best fit
35、 straight line through the peak strength whose slope is the coefficient of Mohr-Coulomb friction angle for peak strengthbetween the two materials where the shearing occurred, or within the GCL. The y-intercept of the straight line is the cohesionintercept for internal shearing or adhesion intercept
36、for interface shearing. A straight line fit for shear stresses at some post-peakdisplacement is the post-peak interface strength between the two materials where the shearing occurred, or the post-peak internalstrength within the GCL. If the post-peak shear stresses have reached a constant value less
37、 than the peak strength, the post-peakstrength is the interface residual strength or the internal residual strength.NOTE 1There may be some investigative cases where only a single test point is desired. If the field design conditions will experience a range ofnormal stresses, it is standard industry
38、 practice to bracket the normal-stress range with tests on both sides of the range, as it is unconservative toextrapolate results outside of the normal-stress range tested. When defining a Mohr-Coulomb shear strength envelope over a range of normal stresses,standard industry practice is to use a min
39、imum of three test points. Attempting to define a single linear Mohr-Coulomb shear strength envelope overtoo-large of a normal-stress range may prove to be problematic in many cases because most failure envelopes exhibit significant curvature over such alarge range, particularly at low normal stress
40、es on the shearing plane.5. Significance and Use5.1 The procedure described in this test method for determination of the shear resistance for the GCL or the GCL interface isintended as a performance test to provide the user with a set of design values for the test conditions examined. The test speci
41、mensand conditions, including normal stresses, are generally selected by the user.5.2 This test method may be used for acceptance testing of commercial shipments of GCLs, but caution is advised as outlinedin 5.2.1.5.2.1 The shear resistance can be expressed only in terms of actual test conditions (s
42、ee Note 1Notes 2 and 3 and Note 2). Thedetermined value may be a function of the applied normal stress, material characteristics, characteristics (for example, of thegeosynthetic), soil properties, size of sample, moisture content, drainage conditions, displacement rate, magnitude of displacement,an
43、d other parameters.NOTE 2In the case of acceptance testing requiring the use of soil, the user must furnish the soil sample, soil parameters, and direct shear testparameters. The method of test data interpretation for purposes of acceptance should be mutually agreed to by the users of this standard.
44、NOTE 3Testing under this test method should be performed by laboratories qualified in the direct shear testing of soils and meeting the requirementsof Practice D3740, especially since the test results may depend on site-specific and test conditions.5.2.2 This test method measures the total resistanc
45、e to shear within a GCL or between a GCL and adjacent material. The totalshear resistance may be a combination of sliding, rolling and interlocking of material components5.2.3 This test method does not distinguish between individual mechanisms, which may be a function of the soil and GCLused,method
46、of material placement and hydration, normal and shear stresses applied, means used to hold the GCL in place, rate ofhorizontal displacement, and other factors. Every effort should be made to identify, as closely as is practicable, the sheared areaand failure mode of the specimen. Care should be take
47、n, including close visual inspection of the specimen after testing, to ensurethat the testing conditions are representative of those being investigated.5.2.4 Information on precision between laboratories is incomplete. In cases of dispute, comparative tests to determine whethera statistical bias exi
48、sts between laboratories may be advisable.5.3 The test results can be used in the design of GCL applications, including but not limited to, the design of liners and capsfor landfills, cutoffs for dams, and other hydraulic barriers.5.4 While the peak strengths and post-peak strengths measured by this
49、 test are generally reproducible by multiple laboratories,theThe displacement at which peak strength and post-peak strength occurs and the shape of the shear stress-horizontal stress versusshear displacement curve may differ considerably from one test device to another due to differences in specimen mounting,gripping surfaces and material preparation. The user of results from this standard is cautioned that results at a specifieddisplacement may not be reproducible across laboratories and that the relative horizontal displacement measu
