ASTM_D_4554_-_12.pdf

Designation:D455412Standard Test Method forIn Situ Determination of Direct Shear Strength of RockDiscontinuities1This standard is issued under the fixed designation D4554;the number immediately following the designation indicates the year oforiginal 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.Scope*1.1 This test method covers the measurement of peak andresidual direct shear strength in a drained condition of in siturock discontinuities as a function of stress normal to thesheared plane.This sheared plane is usually a significantdiscontinuity that may or may not be filled with gouge orsoil-like material.1.2 The measured shear properties are affected by scalefactors.The severity of the effect of these factors must beassessed and applied to the specific problems on an individualbasis.1.3 The values stated in SI units are to be regarded as thestandard.No other units of measurements are included in thisstandard.1.4 All observed and calculated values shall conform to theguidelines for significant digits and rounding established inPractice D6026.1.5 This 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 Documents2.1 ASTM Standards:2D422 Test Method for Particle-Size Analysis of SoilsD653 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 asUsed in Engineering Design and ConstructionD4318 Test Methods for Liquid Limit,Plastic Limit,andPlasticity Index of SoilsD6026 Practice for Using Significant Digits in GeotechnicalDataD6913 Test Methods for Particle-Size Distribution(Grada-tion)of Soils Using Sieve Analysis3.Terminology3.1 Definitions:3.1.1 For definitions of terms used in this test method referto Terminology D653.3.2 Definitions of Terms Specific to This Standard:3.2.1 discontinuitiesany surface across which some prop-erty of the rock mass is not continuous.Discontinuities includejoints,schistosity,faults,bedding planes,cleavage,and zonesof weakness,along with any filling material.3.2.2 peak shear strengththe maximum shear stress in thecomplete curve of stress versus displacement obtained for aspecified constant normal stress.3.2.3 residual shear strengththe shear stress at whichnominally no further rise or fall in shear strength is observedwith increasing shear displacement and constant normal stressas shown in Fig.1.A true residual strength may only bereached after considerably greater shear displacement than canbe achieved in testing.The test value should be regarded asapproximate and should be assessed in relation to the completeshear stress displacement curve.3.2.4 shear strength parameter,capparent cohesion;theprojected intercept on the shear stress axis of the plot of shearstress versus normal stress as shown in Fig.2.3.2.5 shear strength parameter,friction angle;the angleof the tangent to the failure curve at a normal stress that isrelevant to design as shown in Fig.2.3.2.5.1 DiscussionDifferent values of c and relate todifferent stages of a test,for example,c,cr,a,and b,of Fig.2.4.Summary of Test Method4.1 This test method is performed on rectangular-shapedblocks of rock that are isolated on all surfaces,except for theshear plane surface.1This test 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 Aug.1,2012.Published November 2012.Originallyapproved in 1985.Last previous edition approved in 2006 as D4554 02(2006).DOI:10.1520/D4554-12.2For 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 this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 4.2 The blocks are not to be disturbed during preparationoperations.The base of the block coincides with the plane to besheared.4.3 A normal load is applied perpendicular to the shearplane and then a side load is applied to induce shear along theplane and discontinuity.A typical equipment configuration isshown in Fig.3.5.Significance and Use5.1 Because of scale effects,there is no simple method ofpredicting the in situ shear strength of a rock discontinuityfrom the results of laboratory tests on small specimens;in situtests on large specimens are the m