The Research on Strength and Deformation Behaviors of Buffer/Backfill Material under High-Temperature and High-Pressure Conditions

Abstract

"By using thehigh-temperatureandhigh-pressure triaxial apparatus,81 undrainedtriaxialshearingtestsof GMZbentonite were carried out, and the effects of temperature, confining pressure, water content, and dry density on the deformation and strength characteristicsofGMZbentoniteweresystematicallyanalyzed.Fiveresultsarepresentedinthispaper:(1)confiningpressureand drydensity haveagreat influenceonthefailureformsofGMZbentonite; underthenonconfined pressurecondition,thefailure formsofthespecimenarebrittlefailure,anditisthesamewithhighdrydensity,butthespecimenswithlowdrydensityandhigh confiningpressureexhibitplasticfailure;(2)thestrengthofGMZbentonitedecreaseswithincreasingwatercontent;theposition of the deviator stress-axial strain curve under low dry density rises with the increase of temperature, whereas the location of the curveunderhighdrydensitydecreaseswiththeriseoftemperature;(3)initialYoung’smodulusriseswithincreasingtemperature under low dry density, but it is on the contrary under high dry density; with rising water content, initial Young’s modulus generallydecreases;(4)Poisson’sratioriseswithrisingtemperature.TheeffectofdrydensityandwatercontentonPoisson’sratio is insignificant; and (5) the formulae of cohesion and internal friction angle of GMZ bentonite with the changing dry density, watercontent,andtemperatureareproposed,respectively.Theresearchresultsofthispaperprovideascientificbasisforanalyzing the thermo-hydro-mechanical coupling characteristics of buffer materials. "