1、Designation: D5607 16Standard Test Method forPerforming Laboratory Direct Shear Strength Tests of RockSpecimens Under Constant Normal Force1This standard is issued under the fixed designation D5607; the number immediately following the designation indicates the year oforiginal adoption or, in the ca
2、se 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. Scope*1.1 This test method establishes requirements and labora-tory procedures for performing direc
3、t shear strength tests onrock specimens under a constant normal load. It includesprocedures for both intact rock strength and sliding frictiontests, which can be performed on specimens that arehomogeneous, or have planes of weakness, including natural orartificial discontinuities. Examples of an art
4、ificial discontinuityinclude a rock-concrete interface or a lift line from a concretepour. Discontinuities may be open, partially or completelyhealed or filled (that is, clay fillings and gouge). Only onediscontinuity per specimen can be tested. The test is usuallyconducted in the undrained state wi
5、th an applied constantnormal load. However, a clean, open discontinuity may be freedraining, and, therefore, a test on a clean, open discontinuitycould be considered a drained test. During the test, shearstrength is determined at various applied stresses normal to thesheared plane and at various she
6、ar displacements. Relation-ships derived from the test data include shear strength versusnormal stress and shear stress versus shear displacement (shearstiffness).NOTE 1The term “normal force” is used in the title instead of normalstress because of the indefinable area of contact and the minimal rel
7、ativedisplacement between upper and lower halves of the specimen duringtesting. The actual contact areas during testing change, but the actual totalcontact surface is unmeasurable. Therefore nominal area is used forloading purposes and calculations.NOTE 2Since this test method makes no provision for
8、 the measure-ment of pore pressures, the strength values determined are expressed interms of total stress, uncorrected for pore pressure.1.2 This standard applies to hard rock, medium rock, softrock, and concrete.1.3 This test method is only applicable to quasi-static testingof rock or concrete spec
9、imens under monotonic shearing witha constant normal load boundary condition. The constantnormal load boundary condition is appropriate for problemswhere the normal stress is constant along the discontinuity. Theconstant normal load boundary condition may not be appro-priate for problems where shear
10、ing is dilatancy controlled andthe normal stress is not constant along the discontinuity.1.4 All observed and calculated values shall conform to theguidelines for significant digits and rounding established inPractice D6026.1.4.1 The procedures used to specify how data are collected/recorded and cal
11、culated in this standard are regarded as theindustry standard. In addition, they are representative of thesignificant digits that generally should be retained. The proce-dures used do not consider material variation, purpose forobtaining data, special purpose studies, or any considerationsfor the us
12、ers objectives; and it is common practice to increaseor reduce significant digits of reported data to commensuratewith these considerations. It is beyond the scope of these testmethods to consider significant digits used in analysis methodsfor engineering design1.5 UnitsThe values stated in SI units
13、 are to be regardedas standard. The values given in parentheses are mathematicalconversions to inch-pound units, which are provided forinformation only and are not considered standard. Reporting oftest results in units other than SI shall not be regarded asnonconformance with this test method.1.6 Th
14、is standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documen
15、ts2.1 ASTM Standards:2D653 Terminology Relating to Soil, Rock, and ContainedFluidsD2216 Test Methods for Laboratory Determination of Water(Moisture) Content of Soil and Rock by MassD3740 Practice for Minimum Requirements for AgenciesEngaged in Testing and/or Inspection of Soil and Rock as1This test
16、method is under the jurisdiction ofASTM Committee D18 on Soil andRock and is the direct responsibility of Subcommittee D18.12 on Rock Mechanics.Current edition approved Dec. 1, 2016. Published January 2017. Originallyapproved in 1994. Last previous edition approved in 2008 as D5607 08. DOI:10.1520/D
17、5607-16.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.*A Summary of Changes section appears at the end of t
18、his standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopm
19、ent of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1Used in Engineering Design and ConstructionD5079 Practices for Preserving and Transporting Rock CoreSamples (Withdrawn 2017)3D6026 Practice for Using Signifi
20、cant Digits in GeotechnicalDataE4 Practices for Force Verification of Testing MachinesE122 Practice for Calculating Sample Size to Estimate, WithSpecified Precision, the Average for a Characteristic of aLot or Process2.2 ISRM Standard:4Suggested Methods for Laboratory Determination of theShear Stren
21、gth of Rock Joints: Revised Version3. Terminology3.1 DefinitionsFor definitions of common technical termsused in this standard, refer to Terminology D653.3.2 Definitions of Terms Specific to This Standard:3.2.1 apparent stress, nnominal stress, that is, externalload per unit area; calculated by divi
22、ding the externally appliedload by the nominal area.3.2.2 asperity:3.2.2.1 quality, nthe roughness of a surface.3.2.2.2 asperity feature, na surface irregularity rangingfrom sharp or angular to rounded or wavy.3.2.2.3 asperities, nthe collection of a surfaces irregulari-ties that account for the sur
23、faces roughness.3.2.3 discontinuity, nan abrupt change, interruption, orbreak in the integrity or physical properties of rock, such as abedding plane, fracture, cleavage, crack, joint, or fault wherethe opposing rock surfaces may be planar to nonplanar andmatching to misfit.3.2.4 gapped discontinuit
24、y, nconsists of opposing rocksurfaces separated by an open or filled space.3.2.5 tight discontinuity, nconsists of opposing rock sur-faces in intimate and generally continuous contact; it may bevalid to treat such a discontinuity as a single surface.3.2.6 intact shear strength, nthe peak shear resis
25、tance (inunits of stress) of an intact rock specimen or of a specimencontaining a completely healed discontinuity.3.2.7 nominal area, narea obtained by measuring orcalculating the cross-sectional area of the shear plane andcalculated after its relevant cross-sectional dimensions aredetermined.3.2.8
26、residual shear strength, nthe shear stress, (see Fig.1), corresponding to a specific normal stress, for which theshear stress remains essentially constant with increasing sheardisplacement.3.2.8.1 DiscussionIn most cases, the shear stress afterreaching Point A is the residual shear strength.3.2.9 sh
27、ear stiffness, nrepresents the resistance of thespecimen to shear displacements under an applied shear forceprior to reaching the peak shear strength, which is calculatedby dividing the applied apparent shear stress by the resultingshear displacement (slope of the curve prior to peak shearstrength,
28、Fig. 1).3.2.10 sliding friction shear strength, nthe peak shearresistance (in units of stress) of a rock specimen along an opendiscontinuity.4. Summary of Test Method4.1 While maintaining a constant force normal to thenominal shear plane of the specimen, an increasing externalshear force is applied
29、along the designated shear plane to causeshear displacement. The applied normal and shear forces andthe corresponding normal and shear displacements are mea-sured and recorded. These data are the basis for calculating therequired parameters.5. Significance and Use5.1 Determination of shear strength
30、of a rock specimen is animportant aspect in the design of structures such as rock slopes,dam foundations, tunnels, shafts, waste repositories, cavernsfor storage, and other purposes. Pervasive discontinuities(joints, bedding planes, shear zones, fault zones, schistosity) ina rock mass, and genesis,
31、crystallography, texture, fabric, andother factors can cause the rock mass to behave as ananisotropic and heterogeneous discontinuum. Therefore, theprecise prediction of rock mass behavior is difficult.5.2 For nonplanar joints or discontinuities, shear strength isderived from a combination base mate
32、rial friction and overrid-ing of asperities (dilatancy), shearing or breaking of theasperities, and rotations at or wedging of the asperities. Slidingon and shearing of the asperities can occur simultaneously.When the normal force is not sufficient to restrain dilation, theshear mechanism consists o
33、f the overriding of the asperities.When the normal load is large enough to completely restraindilation, the shear mechanism consists of the shearing off of theasperities.5.3 Using this test method to determine the shear strength ofan intact specimen may generate overturning moments whichcould result
34、 in an inclined shear break.3The last approved version of this historical standard is referenced onwww.astm.org.4“ISRM Suggested Methods for Laboratory Determination of the Shear Strengthof Rock Joints: Revised Version”, R. Ulusay (ed.), The ISRM Suggested Methodsfor Rock Characterization, Testing a
35、nd Monitoring: 2007-2014, DOI: 10.1007/978-3-319-07713-0, Springer-Verlag Wien 2013.FIG. 1 Generalized Shear Stress and Shear Displacement CurveD5607 1625.4 Shear strength is influenced by the overburden ornormal pressure; therefore, the larger the overburden pressure,the larger the shear strength.5
36、.5 In some cases, it may be desirable to conduct tests in siturather than in the laboratory to determine the representativeshear strength of the rock mass, particularly when design iscontrolled by discontinuities filled with very weak material. Insitu direct shear testing limits the inherent scale e
37、ffects foundin rock mechanics problems where the laboratory scale maynot be representative of the field scale.5.6 The results can be highly influenced by how the speci-men is treated from the time it is obtained until the time it istested. Therefore, it may be necessary to handle specimens inaccorda
38、nce with Practice D5079 and to document moistureconditions in some manner in the data collection.NOTE 3The quality of the result produced by this standard isdependent on the competence of the personnel performing it, and thesuitability of the equipment and facilities used. Agencies that meet thecrit
39、eria of Practice D3740 are generally considered capable of competentand objective testing/sampling/inspection and the like. Users of thisstandard are cautioned that compliance with Practice D3740 does not initself assure reliable results. Reliable results depend on many factors,Practice D3740 provid
40、es a means of evaluating some of those factors.6. Apparatus6.1 Testing MachineLoading device, to apply and registernormal and shear forces on the specimens. It must haveadequate capability to apply the shear force at a rate conform-ing to the specified requirements in 6.2-6.9. It shall be verifiedat
41、 suitable time intervals in accordance with the proceduresgiven in Practices E4, and comply with the requirementsprescribed therein. The resultant of the shear force passesthrough the center of the intended shear zone or the centroid ofthe shear plane surface area to reduce the potential for adverse
42、moments. If possible, the testing machine should include botha stiff frame and a stiff specimen holder sufficiently rigid toinhibit distortions during testing for accurate determination ofresidual behavior.NOTE 4There are many different direct shear device designs. Al-though details may vary concern
43、ing how to encapsulate specimens intoshear boxes as well as details for assembling the machine, the determi-nations are usually similar.6.2 Fig. 2 is a schematic of an example shear box, anintegral part of the machine.6.3 Load Monitoring DevicesThe load monitoring devices(such as load cells, proving
44、 rings, hydraulic gauges) should beaccurate to within 1 % of the specified load and be calibratedin accordance with Practices E4.6.4 Pressure-Maintaining DeviceA hydraulic componentthat will hold a pressure, within 1 % of the target load, withinthe hydraulic system.6.5 Specimen Holding RingsAluminum
45、 or steel holdingrings (see Fig. 3) with internal dimensions sufficient to accom-modate specimens mounted in an encapsulating medium.6.6 Spacer Plates:6.6.1 Split Spacer PlatesPlastic (or other suitable mate-rial) plates of varying thicknesses for isolating an intactspecimens shear zone from the enc
46、apsulating compound (seeFig. 3).6.6.2 Non-split Spacer PlatesPlastic (or other suitablematerial) plates of varying thicknesses that have a circular oroval hole in the center and are used for non-intact specimens.6.7 Displacement Measuring DeviceLinear variable dif-ferential transformers (LVDTs) may
47、be used as normal andshear displacement measuring devices. Other devices such asdial indicators and direct current differential transformers(DCDTs), are satisfactory. Four devices are used to measurethe normal displacement and provide a check on specimenrotation about an axis parallel to the shear z
48、one and perpen-dicular to the shearing direction. Another device measures theshear displacement. These displacement devices should haveadequate ranges of travel to accommodate the displacements,613 mm (60.5 in.). Sensitivities of these devices should be0.025 mm (0.001 in.) for shear displacement and
49、 0.0025 mm(0.0001 in.) for normal displacement. Make sure that thedevices are located away from the loading direction so as notto be damaged in sudden failures. Measuring devices are to becalibrated/verified at least once a year.6.8 Data Acquisition EquipmentA computer may be usedto control the test, collect data, and plot results. Typical dataacquisition rates are near continuous (greater than 1 Hzsampling rate) with computer based systems.6.9 Computer System (Optional)Capable of 3D contactmeasurements using CAD software.FIG. 2 Schematic Test SetupD
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