1、Designation: D5321/D5321M 13D5321/D5321M 14Standard 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
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.NoteEditorial corrections were made to the units information
3、, Section 3, and throughout the standardon August 23, 2013.1. Scope1.1 This test method covers a procedure for determining the shear resistance of a geosynthetic against soil, or a geosyntheticagainst another geosynthetic, under a constant rate of deformation.1.1.1 The test method is intended to ind
4、icate the performance of the selected specimen by attempting to model certain fieldconditions. Results obtained from this method may be limited in their applicability to the specific conditions considered in thetesting.1.2 The test method is applicable for all geosynthetics, with the exception of ge
5、osynthetic clay liners (GCLs) which areaddressed in Test Method D6243/D6243M.1.3 The test method is not suited for the development of exact stress-strain relationships for the test specimen due to thenon-uniform distribution of shearing forces and displacement.1.4 The values stated in either SI unit
6、s or inch-pound units are to be regarded separately as standard. The values stated in eachsystem may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from thetwo systems may result in non-conformance with the standard.1.5 This standard does
7、not purport to address all the safety concerns, if any, associated with its use. It is the responsibility ofthe user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2
8、D653 Terminology Relating to Soil, Rock, and Contained FluidsD698 Test Methods for Laboratory Compaction Characteristics 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 (2,700k
9、N-m/m3)D2435/D2435M Test Methods for One-Dimensional Consolidation Properties of Soils Using Incremental LoadingD2487 Practice for Classification of Soils for Engineering Purposes (Unified Soil Classification System)D3080/D3080M Test Method for Direct Shear Test of Soils Under Consolidated Drained C
10、onditionsD3740 Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used inEngineering Design and ConstructionD4354 Practice for Sampling of Geosynthetics and Rolled Erosion Control Products(RECPs) for TestingD4439 Terminology for GeosyntheticsD6243
11、/D6243M Test Method for Determining the Internal and Interface Shear Strength of Geosynthetic Clay Liner by the DirectShear Method1 This test method is under the jurisdiction ofASTM Committee D35 on Geosynthetics and is the direct responsibility of Subcommittee D35.01 on Mechanical Properties.Curren
12、t edition approved Aug. 23, 2013Jan. 1, 2014. Published September 2013January 2014. Originally approved in 1992. Last previous edition approved in 20122013as D5321D5321/D5321M1213 DOI: 10.1520/D5321_D5321M-13.10.1520/D5321_D5321M-14.2 For referencedASTM standards, visit theASTM website, www.astm.org
13、, 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 changes
14、 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 official
15、 document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13. Terminology3.1 Definitions: For definitions of terms relating to soil and rock, refer to Terminology D653. For definitions of terms relatingto geosynthetics, refer to Termin
16、ology D4439.3.2 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, nair maintained at a relative humidity between 50 and 70 % and temperature of21 6 2C 70 6 4F.3.2.3 Mohr-Coulomb fricti
17、on angle, , n(angle of friction of a material or between two materials, ) the angle defined by theleast-squares, “best-fit” straight line through a defined section of the shear strength-normal stress failure envelope; the componentof the shear strength indicated by the term , in Coulombs equation, =
18、 ca + n * tan ( ) (see 12.6).3.2.3.1 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 (
19、), to designate the interface friction angle between geosynthetics and soil.3,43.2.4 Mohr-Coulomb shear strength envelope, nthe least squares, “best fit” straight line through a defined section of the shearstrength-normal stress failure envelope described by the equation, = ca + n * tan ( ) (see 12.
20、6). The envelope can be describedfor any chosen shear failure mode (example, peak or post-peak).3.2.5 secant friction angle, sec, n(angle of friction of a material or between two materials, ) the angle defined by a line drawnfrom the origin to a data point on the shear strength-normal stress failure
21、 envelope. Intended to be used only for the normal stresson the shearing plane for which it is defined.3.2.6 shear strength, , nthe shear force on a given failure plane. In the direct shear test it is always stated in relation to thenormal stress acting on the failure plane. Two different types of s
22、hear strengths are often estimated and used in standard practice:3.2.6.1 peak shear strengththe largest value of shear resistance experienced during the test under a given normal stress.3.2.6.2 post-peak shear strengththe minimum, or steady-state value of shear resistance that occurs after the peak
23、shearstrength is experienced.3.2.6.3 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 horizontal displac
24、ement isreached.3.2.7 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).4. Summary of Test Method4.1 The shear resistance between a ge
25、osynthetic and a soil, or other material selected by the user, is determined by placing thegeosynthetic and one or more contact surfaces, such as soil, within a direct shear box. A constant normal stress representative ofdesign stresses is applied to the specimen, and a tangential (shear) force is a
26、pplied to the apparatus so that one section of the boxmoves in relation to the other section. The shear force is recorded as a function of the shear displacement of the moving sectionof the shear box.4.2 To define a Mohr-Coulomb shear strength envelope, it is recommended that a minimum of three test
27、 points be performedat different normal stresses, selected by the user, to model appropriate field conditions. However, there may be instances wherefewer test points are desired (see Note 1). The peak shear stresses, or shear stresses at some post-peak displacement, or both, areplotted against the a
28、pplied normal stresses used for testing. The test data are generally represented by a best fit straight line throughthe peak strength values whose slope is the Mohr-Coulomb friction angle for peak strength between the two materials where theshearing occurred. The y-intercept of the straight line is
29、the adhesion intercept. A straight line fit for shear stresses at somepost-peak displacement is the post-peak interface strength between the two materials where the shearing occurred.NOTE 1There may be some investigative cases where only a single test point is desired. If the field design conditions
30、 will experience 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 to3 LRFD Bridge Design Specifications, 5th Edition, American Association of State Highway and Transportation Officials (AASHT
31、O), Washington, D.C., 2010.4 “Mechanically Stabilized Earth Walls and Reinforced Soil Slopes, Design and Construction Guidelines,”FHWA GEC 011, FHWA NHI-10-024, Vol I, and FHWANHI-10-025, Vol II, U.S. Department of Transportation, Federal Highway Administration (FHWA), Washington, D.C., 2009.D5321/D
32、5321M 142extrapolate 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 minimum of three test points. Attempting to define a single linear Mohr-Coulomb shear strength envelope
33、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 stresses on the shearing plane.5. Significance and Use5.1 The procedure described in this test method for d
34、etermination of the shear resistance of the soil and geosynthetic orgeosynthetic and geosynthetic interface is intended as a performance test to provide the user with a set of design values for thetest conditions examined. The test specimens and conditions, including normal stresses, are generally s
35、elected by the user.5.2 This test method may be used for acceptance testing of commercial shipments of geosynthetics, but caution is advised asoutlined in 5.2.1.5.2.1 The shear resistance can be expressed only in terms of actual test conditions (see Note 2 and Note 3). The determinedvalue may be a f
36、unction of the applied normal stress, material characteristics (for example, of the geosynthetic), soil properties,size of sample, moisture content, drainage conditions, displacement rate, magnitude of displacement, and other parameters.NOTE 2In the case of acceptance testing requiring the use of so
37、il, 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 test method.NOTE 3Testing under this test method should be performed by laboratories qualif
38、ied 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 resistance to shear between a geosynthetic and a supporting material (substratum) ora ge
39、osynthetic and an overlying material (superstratum). The total shear resistance may be a combination of sliding, rolling andinterlocking of material components.5.2.3 This test method does not distinguish between individual mechanisms, which may be a function of the soil andgeosynthetic used, method
40、of material placement and hydration, normal and shear stresses applied, means used to hold thegeosynthetic in place, rate of shear displacement, and other factors. Every effort should be made to identify, as closely aspracticable, the sheared area and failure mode of the specimen. Care should be tak
41、en, including close visual inspection of thespecimen after testing, to ensure that the testing conditions are representative of those being investigated.5.2.4 Information on precision among laboratories is incomplete. In cases of dispute, comparative tests to determine whethera statistical bias exis
42、ts among laboratories may be advisable.5.3 The test results can be used in the design of geosynthetic applications including, but not limited to, the design of liners andcaps for landfills, mining heap leach pads, tailings impoundments, cutoffs for dams and other hydraulic barriers, geosynthetic-rei
43、nforced retaining walls, embankments, and base courses; in applications in which the geosynthetic is placed on a slope; fordetermination of geosynthetic overlap requirements; or in other applications in which sliding may occur between soil and ageosynthetic or between two geosynthetic materials.5.4
44、The displacement at which peak strength and 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
45、this test method is cautioned that results at a specified displacementmay not be reproducible across laboratories and that the relative shear displacement measured in this test at peak strength may notmatch relative shear displacement at peak strength in a field condition.6. Apparatus6.1 Shear Devic
46、eArigid 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 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
47、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 direction parallel to that of the appliedshear force.NOTE 4The position of one of the containers should be adjustable in the normal direction to
48、compensate for vertical deformation of the substrate andgeosynthetic.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 openin
49、g size (in plan)of the geosynthetic tested. The depth of each container that contains soil must be a minimum of 50 mm 2 in. or six times themaximum particle size of 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 geosynthetics andsoils. 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 from scaleor edge effects when compared to t
