ASTM_D_4506_-_21.pdf

Designation:D450621Standard Test Method forDetermining In Situ Modulus of Deformation of a Rock MassUsing the Radial Jacking Test1This standard is issued under the fixed designation D4506;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 is used to determine the in situmodulus of deformation of rock mass by subjecting a testchamber in rock of a circular cross-section to uniformlydistributed radial loading;the consequent rock radial displace-ments are measured at various locations,from which thedeformation modulus may be calculated.The radial anisotropicdeformability of the rock is taken at enough locations that itcan also be determined from the differences between theextensometer readings taken at various locations along andaround the test chamber as well with depth from each loadingsequence.Information on time-dependent deformation may beobtained as well by holding the loads constant for selected timeintervals.NOTE1Deformations caused by a cylindrical test chamber are notlikely uniform even if each steel ring forming the jack is uniformly loaded.Theoretically,the deformations will vary along the cylinder such that itlooks like a gaussian probability curve.1.2 This test method is based upon the procedures devel-oped by the US Bureau of Reclamation,featuring long exten-someters that provide a bottom anchor far enough away fromthe test zone to be used as a zero reference point(Fig.1)(1).2An alternative procedure,the New Austrian method,is alsoavailable and is based on a reference bar going down themiddle to support posts outside the deflection zone due to thetesting loads and shown in Fig.2(2).Other than a differentmethod of taking deformation readings,the two field tests arethe same.Additional information on radial jacking and dataanalysis is presented in References(3-8).1.3 Application of the test results is beyond the scope of thistest method,but may be an integral part of some testingprograms.(See Note 2.)NOTE2For example,in situ stresses around the test tunnel will affectthe test results,depending on how the test results will be used and mayneed to be considered in any analyzes or recommendations.1.4 Testing of the in situ rock deformation behavior islimited by the maximum stress range of the reaction frame andthe flat jacks.1.5 UnitsThe values stated in inch-pound units are to beregarded as standard.The values given in parentheses arerationalized mathematical conversions to SI units that areprovided for information only and are not considered standard.Reporting of test results in units other than inch-pound shallnot be regarded as nonconformance with this test method.1.5.1 The SI units presented for apparatus are substitutionsof the inch-pound units,other similar SI units should beacceptable,providing they meet the technical requirementsestablished by the inch-pound apparatus.1.5.2 The gravitational system of inch-pound units is usedwhen dealing with inch-pound units.In this system,the pound(lbf)represents a unit of force(weight),while the unit for massis slugs.The slug unit is not given unless dynamic(F=ma)calculations are involved.1.5.3 The slug unit of mass is typically not used in com-mercial practice;that is,density,balances,and so on.Therefore,the standard unit for mass in this standard is eitherkilogram(kg)or gram(g)or both.Also,the equivalentinch-pound unit(slug)is not given/presented in parenthesis.1.5.4 It is common practice in the engineering/constructionprofession to concurrently use pounds to represent both a unitof mass(lbm)and of force(lbf).This practice implicitlycombines two separate systems of units;the absolute and thegravitational systems.It is scientifically undesirable to com-bine the use of two separate sets of inch-pound units within asingle standard.As stated,this standard includes the gravita-tional system of inch-pound units and does not use/present theslug unit for mass.However,the use of balances or scalesrecording pounds of mass(lbm)or recording density in lbm/ft3shall not be regarded as nonconformance with this standard.1.5.5 Calculations are done using only one set of units;either SI or gravitational inch-pound.Other units arepermissible,provided appropriate conversion factors are usedto maintain consistency of units throughout the calculations,and similar significant digits or resolution,or both are main-tained.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 Sept.1,2021.Published October 2021.Originallyapproved in 1985.Last previous edition approved in 2013 as D4506 131.DOI:10.1520/D4506-21.2The boldface numbers in parentheses refer to the list of references appended tothis