ASTM_D_7070_-_08.pdf

Designation:D707008Standard Test Methods forCreep of Rock Core Under Constant Stress andTemperature1This standard is issued under the fixed designation D7070;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 These test methods cover the creep behavior of intactsoft and hard rock core in fixed states of stress and temperature.They specify the apparatus,instrumentation,and proceduresfor determining the strain as a function of time under sustainedload.Hard rocks are those with a maximum axial strain atfailure of less than 2%.Soft rocks include such materials assalt and potash,which often exhibit very large strain at failure.1.2 This standard replaces and combines the followingStandard Test Methods now to be referred to as Methods:Method A(D5341 Creep of Hard Rock Core Specimensin Uniaxial Compression at Ambient/Elevated Temperatures);Method B(D4405 Creep of Soft Rock Core Specimens inUniaxial Compression at Ambient or Elevated Temperature);andMethod C(D4406 Creep of Rock Core Specimens inTriaxial Compression at Ambient or Elevated Temperature).1.3 All observed and calculated values shall conform to theguidelines for significant digits and rounding established inPractice D6026.1.3.1 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.1.4 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.1.5 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 to determine theapplicability of regulatory limitations prior to use.For specificprecautionary statements,see Section 7.2.Referenced Documents2.1 ASTM Standards:2D653 Terminology Relating to Soil,Rock,and ContainedFluidsD2113 Practice for Rock Core Drilling and Sampling ofRock for Site InvestigationD2216 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 ConstructionD4543 Practices for Preparing Rock Core as Cylindrical TestSpecimens and Verifying Conformance to Dimensionaland Shape TolerancesD5079 Practices for Preserving and Transporting Rock CoreSamplesD6026 Practice for Using Significant 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 Process3.Terminology3.1 Refer to Terminology D653 for specific definitions.4.Summary of Test Method4.1 A section of rock core specimen is cut to length,and theends are machined flat to produce a cylindrical test specimen.For the Uniaxial Compression Method,the specimen is placedin a loading frame.For Triaxial Compression Method,thespecimen is placed in a triaxial loading chamber and subjectedto confining pressure.If required,the specimen is heated to thedesired test temperature.Axial load is applied rapidly to thespecimen and sustained.Deformation is monitored as a func-tion of elapsed time.1This test method is under the jurisdiction of ASTM Committee D18 and is thedirect responsibility of Subcommittee D18.12 on Rock Mechanics.Current edition approved July 1,2008.Published August 2008.Originallyapproved in 2004.Last previous edition approved in 2004 as D7070 04.DOI:10.1520/D7070-08.2For 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.*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 5.Significance and Use5.1 There are many underground structures that are createdfor permanent or long-term use.Often,these structures aresubjected to an approximately constant load.Creep testsprovide quantitative parameters for stability analysis of thesestructures.5.2 The deformation and strength properties of rock coresmeasured in the laboratory usually do not accurately reflectlarge-scale in situ properties,because the latter are stronglyinfluenced by joints,faults,inhomogeneities,weakness planes,and other factors.Therefore,laboratory values for int