ASTM_D_4729_-_19.pdf

Designation:D472919Standard Test Method forIn Situ Stress and Modulus of Deformation Using the FlatJack Method1This standard is issued under the fixed designation D4729;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 The flat jack test measures the natural or altered in situstress at a rock surface either for a surface outcrop or anunderground excavation surface.The modulus of deformationand the long-term deformational properties(creep)may also beevaluated for the applied stress range,however long-term creepis not covered by this method.1.2 This method covers square flat jacks that are placed in arock slot and if required encapsulated in the slot.1.3 Deformation readings are taken at the surface,but thisstandard does not exclude deformation readings being takenbelow the surface,such as using a flat jack which is set up toobtain displacement data internally.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 or calculated 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 the data,special purpose studies,or any consider-ations for the users objectives;and it is common practice toincrease or reduce significant digits of reported data to becommensurate with these considerations.It is beyond the scopeof this standard to consider significant digits used in analysismethods for engineering design.1.5 LimitationThe flat jack test measures the averagestress normal to the surface of the test chamber,undergroundexcavation,or outcrop.In situ stress levels must be determinedby theoretical interpretations of these data.1.6 Assumptions and Factors Influencing the Data:1.6.1 The stress relief is assumed to be an elastic,reversibleprocess.In nonhomogeneous or highly fractured materials,thismay not be completely true.1.6.2 The equations assume that the rock mass is isotropicand homogeneous.Anisotropic effects may be estimated bytesting in different orientations.1.6.3 The flat jack is assumed to be 100%efficient.Thedesign and size requirements of 7.1 were determined to satisfythis requirement to within a few percent.1.6.4 The jack is assumed to be aligned with the principalstresses on the surface being measured.Shear stresses are notcanceled by jack pressure.Orientating the tests in threedirections in each plane tested prevents the misalignment frombeing excessive for at least one of the tests.1.7 UnitsThe values stated in inch-pound units are to beregarded as standard.The values given in parentheses aremathematical conversions to SI units that are provided forinformation only and are not considered standard.Add ifappropriate,“Reporting of test results in units other thaninch-pounds shall not be regarded as nonconformance with thisstandard.”1.7.1 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.For standards involving the determi-nation of mass or the use of density and unit weight,includethe following numbered paragraph.1.7.2 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 parentheses.1.7.3 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.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 June 1,2019.Published July 2019.Originally approvedin 1987.Last previous edition approved in 2008 as D4729 08,which waswithdrawn July 2017 and reinstated in June 2019.DOI:10.1520/D4729-19.*A Summary of Changes section appears at the end of