1、Designation: D6243/D6243M 13aD6243/D6243M 16Standard Test Method forDetermining the Internal and Interface Shear Strength ofGeosynthetic Clay Liner by the Direct Shear Method1This standard is issued under the fixed designation D6243/D6243M; the number immediately following the designation indicates
2、theyear 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 determin
3、ing 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 deformation.1.2 This test method is intended to indicate the performance of the selected specimen by attempting to model certain fie
4、ldconditions.1.3 This test method is applicable to all GCLs. Remolded or undisturbed soil samples can be used in the test device. See TestMethod D5321D5321/D5321M for non-GCLs.interface shear testing of non-GCL geosynthetics.1.4 This test method is not suited for the development of exact stress-stra
5、in relationships within 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 standard. The values stated in eachsystem may not be exact equivalents; therefore, each system
6、 shall be used independently of the other. Combining values from thetwo 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 of this standard to establish
7、 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 Characteristics of Soil Using Standard Ef
8、fort (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)D2435/D2435M Test Methods for One-Dimensional Consolidation Properties of Soils Using Incremental LoadingD2487 Practice for Classification
9、of Soils for Engineering Purposes (Unified Soil Classification System)D3080/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 and Rock as Used inEngineering Design a
10、nd ConstructionD4439 Terminology for GeosyntheticsD5321D5321/D5321M Test Method for Determining the Shear Strength of Soil-Geosynthetic and Geosynthetic-GeosyntheticInterfaces by Direct ShearD6072/D6072M Practice for Obtaining Samples of Geosynthetic Clay Liners3. Terminology3.1 DefinitionsFor defin
11、itions of terms relating to soil and rock, refer to Terminology D653. For definitions of terms relatingto GCLs, refer to Terminology D4439.1 This test method is under the jurisdiction of ASTM Committee D35 on Geosynthetics and is the direct responsibility of Subcommittee D35.04 on Geosynthetic ClayL
12、iners.Current edition approved July 1, 2013Jan. 1, 2016. Published August 2013January 2016. Originally approved in 1998. Last previous edition approved in 2013 asD6243D6243/D6243M13.13a. DOI: 10.1520/D6243_D6243M-13A.10.1520/D6243_D6243M-16.2 For referencedASTM standards, visit theASTM website, www.
13、astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on 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
14、 changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the
15、official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.2 Definitions of Terms Specific to This Standard:3.2.1 adhesion, ca, nthe y-intercept of the Mohr-Coulomb strength envelope.3.2.2 atmosphere for testing geosynthetics
16、, nair maintained at a relative humidity of between 50 and 70 % and temperatureof 21 6 2C 70 6 4F.3.2.3 GCL, na manufactured hydraulic barrier consisting of clay bonded to a layer, or layers, of geosynthetic materials.3.2.4 Mohr-Coulomb friction angle, , , n(angle of friction of a material or betwee
17、n two materials, degrees) the angle definedby the least-squares, “best-fit” straight line through a defined section of the shear strength-normal stress failure envelope; thecomponent of the shear strength indicated by the term , in Coulombs equation, = Ca + n * tan () (see 12.613.6).3.2.4.1 Discussi
18、onThe 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 (), to designate the interface friction angle
19、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 solid bodies and the normal stressacross th
20、e 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 secant friction angle, sec, n(angle of friction of a material or between
21、two materials, ) the angle defined by a line drawnfrom the origin to a data point on the shear strength-normal stress failure envelope. Intended to be used only for the normal stresson the shearing plane for which it is defined.3.2.7 shear strength, ,nthe shear force on a given failure plane. In the
22、 direct shear test it is always stated in relation to thenormal stress acting on the failure plane. Two different types of shear strengths are often estimated and used in standard practice:3.2.7.1 peak shear strengththe largest value of shear resistance experienced during the test under a given norm
23、al stress.3.2.7.2 post-peak shear strengththe minimum, or steady-state value of shear resistance that occurs 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 res
24、idualshear strength. In some instances, a post-peak shear strength may not be defined before the limit of horizontal 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
25、selected shear failure mode (for example, peak and post-peak).4. 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 surfaces, such as soil
26、, within a direct shear box.Aconstantnormal stress representative of design stresses is applied to the specimen, and a tangential (shear) force is applied to the apparatusso that one section of the box moves in relation to the other section. The shear force is recorded as a function of the horizonta
27、ldisplacement of the moving section of the shear box.4.2 To define a Mohr-Coulomb shear strength envelope, it is recommended that a test points be performed at different normalstresses, selected by the user, to model appropriate field conditions. However, there may be instances where fewer test poin
28、ts aredesired (see Note 1). The peak shear stresses, or shear stresses at some post-peak displacement, or both, are plotted against theapplied normal stresses used for testing. The test data are generally represented by a best fit straight line through the peak strengthwhose slope is the Mohr-Coulom
29、b friction angle for peak strength between the two materials where the shearing occurred, orwithin the GCL. The y-intercept of the straight line is the cohesion intercept for internal shearing or adhesion intercept for interfaceshearing. A straight line fit for shear stresses at some post-peak displ
30、acement is the post-peak interface strength between the twomaterials where the shearing occurred, or the post-peak internal strength within the GCL. If the post-peak shear stresses havereached a constant value less than the peak strength, the post-peak strength is the interface residual strength or
31、the internal residualstrength.3 LRFD Bridge Design Specifications, 5th Edition, 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”Guidelines,”, FHWA
32、 GEC 011, FHWA-NHI-10024, Vol 1 andFHWA-NHI-10025, Vol II, U.S. Department of Transportation, Federal Highway Administration (FHWA), Washington, DC, 2009.D6243/D6243M 162NOTE 1There may be some investigative cases where only a single test point is desired. If the field design conditions will experie
33、nce a range ofnormal stresses, it is standard industry 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 norm
34、al stresses,standard industry practice is to use a minimum 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 ove
35、r such alarge range, particularly at low normal stresses 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 v
36、alues for the test conditions examined. The test specimensand 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 b
37、e expressed only in terms of actual test conditions (see Notes 2 and 3). The determined valuemay be a function of the applied normal stress, material characteristics (for example, of the geosynthetic), soil properties, size ofsample, moisture content, drainage conditions, displacement rate, magnitud
38、e of displacement, and 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 us
39、ers of this standard.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 measure
40、s the total resistance 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 soi
41、l and GCLused,method 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
42、. Care should be taken, 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
43、 statistical bias exists 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 The displacement at which peak strength and
44、post-peak strength occurs and the shape of the shear stress versus sheardisplacement curve may differ considerably from one test device to another due to differences in specimen mounting, grippingsurfaces and material preparation. The user of results from this standard is cautioned that results at a
45、 specified displacement maynot be reproducible across laboratories and that the relative horizontal displacement measured in this test at peak strength may notmatch relative shear displacement at peak strength in a field condition.6. Apparatus6.1 Shear DeviceArigid device to hold the specimen secure
46、ly and in such a manner that a uniform shear force without torquecan be applied to the tested interface. The device consists of both a stationary and moving container, each of which is capable ofcontaining dry or wet soil and are rigid enough to not distort during shearing of the specimen. The trave
47、ling container must beplaced on firm bearings and rack to ensure that the movement of the container is only in a direction parallel to that of the appliedshear force.NOTE 4The position of one of the containers should be adjustable in the normal direction to compensate for vertical deformation of the
48、 GCL, soiland adjacent materials.6.1.1 Square or rectangular containers are recommended. They should have a minimum dimension that is the greatest of 300mm 12 in., 15 times the d85 of the coarser soil used in the test, or a minimum of five times the maximum opening size (in plan)of the geosynthetic
49、tested. The depth of each container should be at least 50 mm 2 in. or six times the maximum particle sizeof the coarser soil tested, whichever is greater.NOTE 5The minimum container dimensions given in 6.1.1 are guidelines based on requirements for testing most combinations of GCLs and adjacentmaterials. Containers smaller than those specified in 6.1.1 can be used if it can be shown that data generated by the smaller devices contain no bias fromscale or edge effects when compared to the minimum size devices specified in 6.1.1 for specif
