ASTM_D_4971_-_08.pdf

Designation:D497108Standard Test Method forDetermining In Situ Modulus of Deformation of Rock UsingDiametrically Loaded 76-mm(3-in.)Borehole Jack1This standard is issued under the fixed designation D4971;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 estimation of in situmodulus of a rock mass at various depths and orientations.Information on time-dependent deformation may also be ob-tained.1.2 All observed and calculated values shall conform to theguidelines for significant digits and rounding established inPractice D6026.1.2.1 The method used to specify how data are collected,calculated,or recorded in this standard is not directly related tothe accuracy to which the data can be applied in design or otheruses,or both.How one applies the results obtained using thisstandard is beyond its scope.1.3 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are mathematicalconversions to inch-pound units that are provided for informa-tion only and are not considered standard.1.4 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:2D653 Terminology Relating to Soil,Rock,and ContainedFluidsD3740 Practice for Minimum Requirements for AgenciesEngaged in Testing and/or Inspection of Soil and Rock asUsed in Engineering Design and ConstructionD6026 Practice for Using Significant Digits in GeotechnicalDataD6032 Test Method for Determining Rock Quality Designa-tion(RQD)of Rock Core3.Terminology3.1 See Terminology D653 for general definitions.3.2 Definitions of Terms Specific to This Standard:3.2.1 deformationchange in shape or size,(see Terminol-ogy D653).In this test method deformation is the change in thediameter of the borehole.3.2.2 modulus of deformationratio of stress to strain for amaterial under given loading conditions;numerically equal tothe slope of the tangent or the secant of the stress-strain curve.The use of the term modulus of elasticity is recommended formaterials that deform in accordance with Hookes law,and theterm modulus of deformation is recommended for materialsthat deform otherwise,(see Terminology D653).In this testmethod,the modulus of deformation is calculated from theapplied fluid pressure,the relative change in hole diameter,afunction of Poissons ratio,and a constant.3.2.3 jack effciencyratio of the jack plate pressure to theapplied hydraulic pressure.4.Summary of Test Method4.1 The 76 mm(3.0 in.)jacks,(see Fig.1 and Fig.2),induceundirectional pressure to the walls of a borehole by means oftwo opposed curved steel platens each covering a 90 sector,over a length of 20.3 cm(8 in.).4.2 Raw data from a test consist of hydraulic-line pressure,Qh,versus readout from linear variable differential transform-ers(LVDTs)measuring platen movement.Knowing the dis-placement calibration of the LVDTs,the raw data can betransformed to a test record of hydraulic pressure versus holediameter,D.For each increment of pressure,Qh,and holedeformation,D,theoretical data analysis(1),3assuming rigidjack plates and full 90 contact,give the theoretical rock massmodulus,E(Etheoretical)as a function E=f(QhD T*),where T*is a coefficient dependent upon Poissons ratio.If Eis measured on a linear segment of the loading curve,common1This 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 July 1,2008.Published July 2008.Originally approvedin 1989.Last previous edition approved in 2006 as D4971 02(2006).DOI:10.1520/D4971-08.2For 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.3The boldface numbers in parentheses refer to a list of references at the end ofthe standard.*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 terminology is modulus of deformation.If E is measured on anunloading linear segment,it is referred to as the recoverymodulus.5.Significance and Use5.1 Results of this test method are used to predict displace-ments in rock mass caused by loads from a structure or fromunderground construction.It is one of several tests that shouldbe performed.5.2 Because the jack can apply directed loads,this testmethod can be perform