Designation:D7608−10StandardTestMethodforTorsionalRingShearTesttoDetermineDrainedFullySoftenedShearStrengthandNonlinearStrengthEnvelopeofCohesiveSoils(UsingNormallyConsolidatedSpecimen)forSlopeswithNoPreexistingShearSurfaces1ThisstandardisissuedunderthefixeddesignationD7608;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1Thistestmethodprovidesaprocedureforperformingatorsionalringsheartestunderadrainedconditiontodeterminethefullysoftenedshearstrengthandnonlinearstrengthenve-lopeofcohesivesoils.Thefullysoftenedstrengthisusedtoevaluatethestabilityofslopesthatdonothaveapreexistingshearsurface.Inaddition,thefullysoftenedshearstrengthcorrespondstothepeakshearstrengthofanormallyconsoli-datedspecimen.Thistestmethodfocusesontheuseofareconstitutedspecimentomeasurethefullysoftenedstrength.Thistestmethodisperformedbyshearinganormallyconsoli-dated,reconstitutedspecimenatacontrolleddisplacementrateuntilthepeakshearresistancehasbeenobtained.Generally,thedrainedfullysoftenedfailureenvelopeisdeterminedatthreeormoreeffectivenormalstresses.Aseparatetestspeci-menmustbeusedforeachnormalstresstomeasurethefullysoftenedstrengthotherwiseapost-peakorevenresidualstrengthwillbemeasuredifthesamespecimenisusedbecauseoftheexistenceofashearsurface.1.2Theringshearapparatusallowsareconstitutedspeci-mentobenormallyconsolidatedatthedesirednormalstresspriortodrainedshearing.Thissimulatesthefieldconditionsunderwhichthefullysoftenedstrengthdevelopsinovercon-solidatedclays,claystones,mudstones,andshales.1.3Ashearstress-displacementrelationshipmaybeob-tainedfromthistestmethod.However,ashearstress-strainrelationshiporanyassociatedquantity,suchasmodulus,cannotbedeterminedfromthistestmethodbecausepossiblesoilextrusionandvolumechangepreventsdefiningtheheightneededintheshearstraincalculations...
