1、Designation: D6243 09D6243 13Standard Test Method forDetermining the Internal and Interface Shear Resistance ofGeosynthetic Clay Liner by the Direct Shear Method1This standard is issued under the fixed designation D6243; the number immediately following the designation indicates the year oforiginal
2、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 the internal she
3、ar 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 constant stress.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.1.4 This test method is not suited for the development of exact stress-strain relationships within the test specimen due to thenonuniform distribution of shearing forces a
5、nd displacement.1.5 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.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 standa
6、rd 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 Characteristics of Soil Us
7、ing 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)D2435 Test Methods for One-Dimensional Consolidation Properties of Soils Using Incremental LoadingD2487 Practice for Classif
8、ication of Soils for Engineering Purposes (Unified Soil Classification System)D3080 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
9、and ConstructionD4439 Terminology for GeosyntheticsD6072 Practice for Obtaining Samples of Geosynthetic Clay Liners3. Terminology3.1 DefinitionsFor definitions of terms relating to soil and rock, refer to Terminology D653. For definitions of term relatingto GCLs, refer to Terminology D4439.3.2 Defin
10、itions of Terms Specific to This Standard:3.2.1 adhesion, ca, nthe shearing resistance between two unlike materials under zero normal stress.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 s
11、hear stress that resists slippage internal to a body or between two solid bodies at rest with respectto each other and the normal stress across the contact surface.1 This test method is under the jurisdiction of ASTM Committee D35 on Geosynthetics and is the direct responsibility of Subcommittee D35
12、.04 on Geosynthetic ClayLiners.Current edition approved Nov. 1, 2009Jan. 1, 2013. Published January 2010February 2012. Originally approved in 1998. Last previous edition approved in 20082009 asD624308a.09. DOI: 10.1520/D6243-09.10.1520/D6243-13.2 For referencedASTM standards, visit theASTM website,
13、www.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
14、what 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
15、the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.2.3 atmosphere for testing geosynthetics, nair maintained at a relative humidity of between 50 and 70 % and temperatureof 21 6 2C (70 6 4F).3.2.4 coeffcient of fr
16、iction, na constant proportionality factor relating shear to normal stress for a defined failure condition.3.2.5 cohesion c, nshear strength of material, or the interface between two materials, at zero normal stress; the component ofthe shear strength indicated by the term c, in Coulombs equation =
17、c + n tan ().3.2.6 direct shear friction test, nfor GCLs, a procedure in which the internal GCL or the interface between a GCL and anyother surface, under a constant normal stress specified by the user, is stressed to failure by the relative movement of one surfaceagainst the other for interface str
18、ength and by internal shear for internal strength.3.2.7 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 withcontinue
19、d shearing.3.2.9 post-peak strength, nvalues of shear stress at some displacement beyond the peak shear strength where the shear stressapproaches a constant value with continued displacement.4. Summary of Test Method4.1 The shear resistance internal to the GCLor between a GCLand adjacent material, o
20、r between any GCLcombination selectedby the user, is determined by placing the GCL and one or more contact surfaces, such as soil, within a direct shear box.Aconstantnormal stress representative of field stresses is applied to the specimen, and a tangential (shear) force is applied to the apparatuss
21、o that one section of the box moves in relation to the other section. The shear force is recorded as a function of the horizontaldisplacement of the moving section of the shear box.4.2 The test is performed for a minimum of three different normal stresses, selected by the user, to model appropriate
22、fieldconditions. The peak shear stresses, or shear stresses at some post-peak displacement, or both, are plotted against the appliednormal stresses used for testing. The test data are generally represented by a best fit straight line through the peak strength whoseslope is the coefficient of frictio
23、n for peak strength between the two materials where the shearing occurred, or within the GCL.The y-intercept of the straight line is the cohesion intercept for internal shearing or adhesion intercept for interface shearing. Astraight line fit for shear stresses at some post-peak displacement is the
24、post-peak interface strength between the two materialswhere the shearing occurred, or the post-peak internal strength within the GCL. If the post-peak shear stresses have reached aconstant value less than the peak strength, the post-peak strength is the interface residual strength or the internal re
25、sidual strength.5. Significance and Use5.1 The procedure described in this test method for the shear resistance for the GCL or the GCL interface is intended as aperformance test to provide the user with a set of design values for the test conditions examined.The test specimens and conditions,includi
26、ng 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 (see Note 1 and Note 2). The
27、determinedvalue may be a function of the applied normal stress, material characteristics, size of sample, moisture content, drainage conditions,displacement rate, magnitude of displacement, and other parameters.NOTE 1In the case of acceptance testing requiring the use of soil, the user must furnish
28、the soil sample, soil parameters, and direct shear testparameters.NOTE 2Testing 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 t
29、est conditions.5.2.2 This test method measures 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 m
30、echanisms, which may be a function of the soil 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
31、 sheared areaand failure mode of the specimen. 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 dis
32、pute, comparative tests to determine whethera 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
33、 While the peak strengths and post-peak strengths measured by this test are generally reproducible by multiple laboratories,the displacement at which peak strength and post-peak strength occurs and the shape of the shear stress-horizontal displacementD6243 132curve may differ considerably from one t
34、est device to another due to differences in specimen mounting, gripping surfaces andmaterial preparation. The user of results from this standard is cautioned that results at a specified displacement may not bereproducible across laboratories and that the relative horizontal displacement measured in
35、this test at peak strength may not matchrelative horizontal displacement at peak strength in a field condition.6. Apparatus6.1 Shear DeviceArigid device to hold the specimen securely and in such a manner that a uniform shear force without torquecan be applied to the tested interface. The device cons
36、ists 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 traveling container must beplaced on firm bearings and rack to ensure that the movement of the container is only in a directi
37、on parallel to that of the appliedshear force.NOTE 3The position of one of the containers should be adjustable in the normal direction to compensate for vertical deformation of the GCL, soiland adjacent materials.6.1.1 Square or rectangular containers are recommended. They should have a minimum dime
38、nsion that is the greater of 300 mm(12 in.), 15 times the d35 of the coarser soil used in the test, or a minimum of five times the maximum opening size (in plan) ofthe geosynthetic tested. The depth of each container should be at least 50 mm (2 in.) or six times the maximum particle size ofthe coars
39、er soil tested, whichever is greater.NOTE 4The 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 smal
40、ler devices contain no bias fromscale or edge effects when compared to the minimum size devices specified in 6.1.1. The user should conduct comparative testing prior to the acceptanceof data produced on smaller devices. For direct shear testing involving soils, competent geotechnical review is recom
41、mended to evaluate the compatibilityof the minimum and smaller direct shear devices.6.2 Normal Stress Loading Device, capable of applying and maintaining a constant uniform normal force on the specimen forthe duration of the test. Careful control and accuracy (62 %) of normal force is important. Nor
42、mal force loading devices include,but are not limited to, weights, pneumatic or hydraulic bellows, or piston-applied stresses. For jacking systems, the tilting ofloading plates must be limited to less than 2 from the shear direction during shearing. The device must be calibrated to determinethe norm
43、al force delivered to the shear plane.6.3 Shear Force Loading Device, capable of applying a shearing force to the specimen at a constant rate of horizontaldisplacement. The horizontal force measurement system must be calibrated, including provisions to measure and correct for theeffects of friction
44、and tilting of the loading system. The rate of displacement should be controlled to an accuracy of 610 % overa range of at least 6.35 mm/min (0.25 in./min) to 0.025 mm/min (0.001 in./min). The system must allow constant measurementand readout of the applied shear force. An electronic load cell or pr
45、oving ring arrangement is generally used. The shear forceloading device should be connected to the test apparatus in such a fashion that the point of the load application to the travelingcontainer is in the plane of the shearing interface and remains the same for all tests. (See Note 5).NOTE 5The op
46、erating range of normal stresses for a device should be limited to between 10 and 90 % of its calibrated range. If a device is usedoutside this range, the report shall so state and give a discussion of the potential effect of uncertainties in normal stress on the measured results.6.4 Displacement In
47、dicators, for providing continuous readout of the horizontal shear displacement, and if desired, verticaldisplacement of the specimen during the consolidation or shear phase, or both. Displacement indicators, such as dial indicators,or linear variable differential transformers (LVDTs), capable of me
48、asuring a displacement of at least 75 mm (3 in.) for horizontaldisplacement and 25 mm (1 in.) for vertical displacement are recommended. The sensitivity of displacement indicators should beat least 0.02 mm (0.001 in.) for measuring horizontal displacement and 0.002mm (0.0001 in.) for measuring verti
49、cal displacement.6.5 GCL Clamping Devices, required for fixing GCL specimens to the stationary section or container, the traveling container,or both, during shearing of the specimen. Clamps and grips shall not interfere with the shearing surfaces within the shear box andmust keep the GCL specimens flat during testing. Gripping surfaces must develop sufficient shear resistance to preventnon-uniform displacement of the GCL and adjacent geosynthetics. Gripping surfaces must develop sufficient shear resistance toprevent tensile failure within any geosynthet
