ASTM_D_8359_-_21.pdf

Designation:D835921Standard Test Method forDetermining the In Situ Rock Deformation Modulus andOther Associated Rock Properties Using a FlexibleVolumetric Dilatometer1This standard is issued under the fixed designation D8359;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 Thistestmethodestablishestheguidelines,requirements,procedure,and analyses for determining the insitu deformation modulus of a rock mass and other ancillarydata using a flexible volumetric dilatometer in an N-size,75.7mm(2.98 in.)drill hole(Fig.1 and Fig.2).Cyclic,creep,andunloading cycles are not covered in detail in this standard butmay be added in the future or with a separate test standard,practice,or guide.NOTE1Other rock mass deformability tests are radial jack tests,flatjack tests,flexible plate tests,and borehole jack tests.1.2 This test method applies mainly to a commerciallyavailable flexible,volumetric dilatometer for an N-size,(75.7-mm(2.98-in.)I.D.)borehole that is inflated and deflatedhydraulically in the borehole.However,the test method couldapply to other dilatometers,including pneumatically inflated,or for different borehole sizes as well as covered under theBritish Standards Institute EN ISO 22476-5(https:geotech-nicaldesign.info).Use of a different diameter or type ofvolumetric dilatometer is up to the owner or project managerand shall not be regarded as nonconformance with this stan-dard.1.3 Purpose,Application,Range of Uses,and Limitations:1.3.1 This designation is described in the context of obtain-ing data for the design,construction,or maintenance ofstructures on or in rock.This method can be conducted in anyorientation but is usually conducted in a vertical or horizontalborehole as dictated by the design consideration.1.3.2 The test has no depth limits other than those imposedby the limitations of the test equipment,drill hole quality,testing personnel,and equipment to drill the holes and positionthe testing assembly.1.3.3 Since this is a volumetric test,only the averagedeformation is obtained around the borehole.If the rockproperties,for any reason,including the in situ stress field orfracture density,are significantly anisotropic,then this devicecannot detect that difference.1.3.4 Alarge expansion of the probe in a test zone can occurdue to either an oversized drill hole,weathering,lithology,ordiscontinuities.As a result,the maximum pressure and expan-sion of the dilatometer would be limited.For example,for oneparticular dilatometer to avoid damaging the membrane in apreferred N-size,75.7 mm(2.98 in.)I.D.,borehole,themaximum working pressure of 30,000 kPa(4,350 lbf/in.2)might be possible.In contrast,at 82.5 mm(3.25 in.),themaximum working pressure would drop to only 20,680 kPa(3000 lbf/in.2).Furthermore,regardless of if it an oversizeddrill hole or a low modulus test interval,the maximumdiameter(inflated)of only 85.5 mm(3.37 in.)is allowed.1.3.5 The radial displacements of the borehole walls duringpressurization are calculated from the total volume change ofthe dilatometer.As such,the test results from a volumetricdilatometer indicates only the averaged value of the modulus ofdeformation.1.3.6 The volumetric dilatometer test does not provide theanisotropic properties of the rock mass because it measures theaverage deformation and not the deformation in specificdirections.However,by conducting dilatometer tests in bore-holes oriented in different directions or taking impressionpacker data in any test intervals that had developed a hydraulictype fracture,some aspects of the in situ anisotropic conditionscould be obtained.1.4 UnitsThe values stated in SI units are to be regardedas standard.The values given in parentheses are provided forinformation only and are not considered standard.Reporting oftest results in units other than SI shall not be regarded asnonconformance with this standard.1.4.1 The gravitational system of inch-pound units is usedwhen dealing with inch-pound units.In the system,the pound(lbf)represents a unit of force(weight),while the units formass is slugs.The slug unit is not given,unless dynamic(F=ma)calculations are involved.1.5 All observed and calculated values shall conform to theguidelines for significant digits and rounding established inPractice D6026.1These test methods are under the jurisdiction ofASTM Committee D18 on Soiland Rock and are the direct responsibility of Subcommittee D18.12 on RockMechanics.Current edition approved Aug.15,2021.Published August 2021.Originallyapproved in 2020.Last previous edition approved in 2020 as D8359-20.DOI:10.1520/D8359-21.*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 StatesThis i