1、Designation: D532108 D532112 Standard Test Method for Determining the Coefficient Shear Strength of Soil and Geosynthetic or Geosynthetic and Geosynthetic Friction by the Direct Shear MethodSoil-Geosynthetic and Geosynthetic-Geosynthetic Interfaces by Direct Shear 1 This standard is issued under the
2、 xed designation D5321; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A superscript epsilon () indicates an editorial change since the last r
3、evision or reapproval. 1. Scope 1.1 This test method covers a procedure for determining the shear resistance of a geosynthetic against soil, or a geosynthetic against another geosynthetic, under a constant rate of deformation. 1.1.1 The test method is intended to indicate the performance of the sele
4、cted specimen by attempting to model certain eld conditions. Results obtained from this method may be limited in their applicability to the specic conditions considered in the testing. 1.2 The test method is applicable for all geosynthetics. geosynthetics, with the exception of geosynthetic clay lin
5、ers (GCLs) which are addressed in Test Method D6243. 1.3 The test method is not suited for the development of exact stress-strain relationships for the test specimen due to the non-uniform distribution of shearing forces and displacement. 1.4 The values stated in SI units are to be regarded as the s
6、tandard. The values given in parentheses are for information only. 1.5 This standard does not purport to address all the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the appl
7、icability of regulatory limitations prior to use. 2. Referenced Documents 2.1 ASTM Standards: 2 D653Terminology Relating to Soil, Rock, and Contained Fluids D698Test Methods for Laboratory Compaction Characteristics of Soil Using Standard Effort (12 400 ft-lbf/ft 3 (600 kN-m/m 3 ) D1557Test Methods
8、for Laboratory Compaction Characteristics of Soil Using Modied Effort (56,000 ft-lbf/ft 3 (2,700 kN-m/m 3 ) D2435Test Methods for One-Dimensional Consolidation Properties of Soils Using Incremental Loading D3080Test Method for Direct Shear Test of Soils Under Consolidated Drained Conditions D3740Pra
9、ctice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used in Engineering Design and Construction D4354Practice for Sampling of Geosynthetics and Rolled Erosion Control Products(RECPs) for Testing D4439Terminology for Geosynthetics D6243TestMethodforDet
10、erminingtheInternalandInterfaceShearResistanceofGeosyntheticClayLinerbytheDirectShear Method 3. Terminology 3.1 Denitions: For denitions of terms relating to soil and rock, refer to Terminology D653. For denitions of terms relating to geosynthetics, refer to Terminology D4439. 1 Thistestmethodisunde
11、rthejurisdictionofASTMCommitteeD35onGeosyntheticsandisthedirectresponsibilityofSubcommitteeD35.01onMechanicalProperties. Current edition approved July 1, 2008July 1, 2012. Published August 2008July 1, 2012. Originally approved in 1992. Last previous edition approved in 20022008 as D53210208 DOI: 10.
12、1520/D5321-08.10.1520/D5321-12. 2 ForreferencedASTMstandards,visittheASTMwebsite,www.astm.org,orcontactASTMCustomerServiceatserviceastm.org.ForAnnualBookofASTMStandards volume information, refer to the standards Document Summary page on the ASTM website. This document is not anASTM standard and is i
13、ntended only to provide the user of anASTM standard an indication of what changes have been made to the previous version. Because it 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 cu
14、rrent version of 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 States 13.2 Denitions of Terms Specic to This Standard: 3.2.1 adhesion, c a nshear strength envelop
15、e, n the shearing resistance between two adjacent materials under zero normal stress.Practically,thisisdeterminedasthey-interceptofastraightlinerelatingthelimitingvalueofshearstressthatresistslippage between two materials and the normal stress across the contact surface of the two materials., curvi-
16、linear line on the shear stress-normal stress plot representing the combination of shear and normal stresses that dene a selected shear failure mode (for example, peak and post-peak). (D653, D-18) 3.2.2 adhesion, c a , nthe y-intercept of the Mohr-Coulomb strength envelope. 3.2.3 angleoffriction,Moh
17、r-Coulombshearstrengthenvelope,n(angleoffrictionbetweentwomaterials)(degrees)theangle whose tangent is the slope of the line relating limiting value of the shear stress that resists slippage between two solid bodies and the normal stress across the contact surface of the two bodies. Limiting value m
18、ay be at the peak shear stress or at some other failure condition dened by the user of the test results. This is commonly referred to as interface friction angle. (D653, D-18) 3.2.4 Mohr-Coulomb friction angle, d, n(angle of friction of a material or between two materials, degrees) the angle dened b
19、y the least-squares, best-t straight line through a dened section of the shear strength-normal stress failure envelope; the component of the shear strength indicated by the term d, in Coulombs equation, t = c a + s n tan (d ) (see 12.6). NOTE 1The end user is cautioned that some organizations (for e
20、xample, FHWA, AASHTO along with state agencies who using these documents) are currently using the Greek letter, Delta (d), to designate wall-backll interface friction angle and the Greek letter, Rho (r), to designate the interface friction angle between geosynthetics and soil (Reference: AASHTO, 201
21、0. LRFD Bridge Design Specications, 5th Edition, American Association of StateHighwayandTransportationOfficials,Washington,D.C.andFHWA,2009.MechanicallyStabilizedEarthWallsandReinforcedSoilSlopes,Design and Construction Guidelines, U.S. Department of Transportation, Federal Highway Administration, W
22、ashington DC, FHWA NHI-10-024 Vol I, NHI-10-025 Vol II, and as FHWA GEC011). 3.2.5 atmosphere for testing geosynthetics, nair maintained at a relative humidity of 6565% and temperature of 2162C (7064F). between 50 and 70 % and temperature of 21 6 2C (70 6 4F). (D4439) 3.2.6 coeffcient of friction,sh
23、ear strength, t, nThe slope of the line relating limiting value of the shear stress that resists slippage between two materials andthe shear force on a given failure plane. In the direct shear test it is always stated in relation to the normal stress across the contact surface of the two bodies. Lim
24、iting value may be at the peak shear stress or at some other failureconditiondenedbytheuser.actingonthefailureplane.Twodifferenttypesofshearstrengthsareoftenestimatedandused in standard practice: peak shear strength: the largest value of shear resistance experienced during the test under a given nor
25、mal stress. post-peak shear strength: the minimum, or steady-state value of shear resistance that occurs after the peak shear strength is experienced. NOTE 2The end user is cautioned that the reported value of post-peak shear strength (regardless how dened) is not necessarily the residual shear stre
26、ngth. In some instances, a post-peak shear strength may not be dened before the limit of horizontal displacement is reached. (D653, D-18) 3.2.5 direct shear friction test, nfor geosynthetics, a procedure in which the interface between a geosynthetic and any other surface, under a range of normal str
27、esses specied by the user, is stressed to failure by the horizontal movement of one surface against the other. 3.2.7 geosynthetic, secant friction angle, d sec , na planar synthetic product manufactured from polymeric material used with soil, rock, earth, or other geotechnical engineering-related ma
28、terial as an integral part of a man-made project, structure, or system. (angle of friction of a material or between two materials, ) the angle dened by a line drawn from the origin to a data point on the 2shear strength-normal stress failure envelope. Intended to be used only for the normal stress o
29、n the shearing plane for which it is dened. (D4439) 3.2.7 limiting value, nthe value of shear stress at some condition, such as the peak value, the ultimate value, or the value at some prescribed displacement. 4. Summary of Test Method 4.1 The shear resistance between a geosynthetic and a soil, or o
30、ther material selected by the user, is determined by placing the geosyntheticandoneormorecontactsurfaces,suchassoil,withinadirectshearbox.Aconstantnormalforcestressrepresentative of design stresses is applied to the specimen, and a tangential (shear) force is applied to the apparatus so that one sec
31、tion of the box moves in relation to the other section. The shear force is recorded as a function of the horizontalshear displacement of the moving section of the shear box. 4.2 The test is performed at a minimum of three To dene a Mohr-Coulomb shear strength envelope, it is recommended that a test
32、points be performed at different normal stresses, selected by the user, to model appropriate eld conditions. The limiting valuesofshearstressesHowever,theremaybeinstanceswherefewertestpointsaredesired(seeNote3).Thepeakshearstresses, or shear stresses at some post-peak displacement, or both, are plot
33、ted against the applied normal compressive stresses used for testing. The test data are generally represented by a best t straight line through the peak strength values whose slope is the coefficient of friction Mohr-Coulomb friction angle for peak strength between the two materials where the sheari
34、ng occurred.The D5321 12 2y-intercept of the straight line is the adhesion.adhesion intercept. A straight line t for shear stresses at some post-peak displacement is the post-peak interface strength between the two materials where the shearing occurred. NOTE 3There may be some investigative cases wh
35、ere only a single test point is desired. If the eld design conditions will experience a range of normal stresses, it is standard industry practice to bracket the normal-stress range with tests on both sides of the range, as it is unconservative to extrapolate results outside of the normal-stress ran
36、ge tested. When dening a Mohr-Coulomb shear strength envelope over a range of normal stresses, standard industry practice is to use a minimum of three test points. Attempting to dene a single linear Mohr- Coulomb shear strength envelope over too-large of a normal-stress range may prove to be problem
37、atic in many cases because most failure envelopes exhibit signicant curvature over such a large range, particularly at low normal stresses on the shearing plane. 5. Signicance and Use 5.1 Theproceduredescribedinthistestmethodfordeterminationofthecoefficientshearresistanceofthesoilandgeosynthetic or
38、geosynthetic and geosynthetic friction by the direct shear method interface is intended as a performance test to provide the user with a set of design values for the test conditions examined. The test specimens and conditions, including normal stresses, are generally selected by the user. 5.2 This t
39、est method may be used for acceptance testing of commercial shipments of geosynthetics, but caution is advised as outlined below.in 5.2.1. 5.2.1 The coefficient of soil and geosynthetic friction shear resistance can be expressed only in terms of the soil used in testing actualtestconditions(seeNote1
40、4andNote25).Thedeterminedvaluemaybeafunctionoftheappliednormalstress,geosynthetic material characteristics, soil gradation, soil plasticity, density, moisture content,material characteristics (for example, of the geosynthetic), soil properties, size of sample, drainage conditions, displacement rate,
41、 magnitude of displacement, and other parameters. NOTE 4In the case of acceptance testing requiring the use of soil, the user must furnish the soil sample, soil parameters, and direct shear test parameters. The method of test data interpretation for purposes of acceptance should be mutually agreed t
42、o by the users of this standard. NOTE 5Testing under this standard test method should be performed by laboratories experiencedqualied in the direct shear testing of soils and meeting the requirements of Practice D3740, especially since the test results may depend on site-specic and test conditions.
43、5.2.2 This test method measures the total resistance to shear between a geosynthetic and a supporting material (substratum) or a geosynthetic and an overlying material (superstratum). Total sliding The total shear resistance may be a combination of sliding, rolling, interlocking of soil particles an
44、d geosynthetic surfaces, and shear strain within the geosynthetic specimen. Shearing resistance may be different on the two faces of a geosynthetic and may vary with direction of shearing relative to orientation of the geosynthetic. rolling and interlocking of material components. 5.2.3 TheThis test
45、 method does not distinguish between individual mechanisms, which may be a function of the soil and geosynthetic used, method of soil placement, material placement and hydration, normal and shear stresses applied, rate of horizontalmeans used to hold the geosynthetic in place, rate of shear displace
46、ment, and other factors. Every effort should be made to identify and record with a sketch, identify, as closely as is practicable, the sheared area and failure mode of the specimen. Care should be taken, including close visual inspection of the specimen after testing, to ensure that the testing cond
47、itions are representative of those being investigated. 5.2.4 Information on precision betweenamong laboratories is incomplete. In cases of dispute, comparative tests to determine whether a statistical bias exists betweenamong laboratories may be advisable. 5.3 The test method produces test data that
48、 results can be used in the design of geosyntheicgeosynthetic applications, including but not limited to: the design of liners and caps for landlls, mining heap leach pads, tailings impoundments, cutoffs for dams and other hydraulic barriers, geosynthetic-reinforced retaining walls, embankments, and
49、 base courses; in applications in which the geosyntheticisplacedonaslope;fordeterminationofgeosyntheticoverlaprequirements;orinotherapplicationsinwhichsliding may occur between soil and a geosynthetic or between two geosynthetic materials. 5.4 The displacement at which peak strength and post-peak strength occurs and the shape of the shear stress vs. shear displacement curve may differ considerably from one test device to another due to differences in specimen mounting, gripping surfaces and material preparation. The user
