砂岩变形率与水理效应的力学特性研究
Effects of deformation rate and hydrated condition on the mechanical property of sandstone
-
摘要: 通过不同变形加载速率下干燥和饱水岩样的单轴压缩试验,研究了砂岩抗压强度、 弹性模量、峰后应变和声发射特性的变形率效应和水理效应,定义力学参数的强化和弱化 因子,建立考虑砂岩变形率和水理效应的一维本构模型并进行验证。 结果表明:① 干燥砂 岩的应力-应变曲线包括弹性、弱塑性和破裂三个阶段,饱水砂岩则出现较长压实阶段,同 时弹性阶段缩短,塑性阶段增长。 ② 加载速率对干燥和饱水砂岩的抗压强度均具有强化作 用,抗压强度的率效应强化因子随加载速率的增大而增大;水对砂岩抗压强度具有弱化作 用,且水理效应弱化因子随加载速率的增大而增大;随着加载速率的增大,干燥和饱水砂岩 抗压强度的差值逐渐减小。 ③ 加载速率对干燥和饱水砂岩的弹性模量均具有强化作用,且 随加载速率呈线性增大趋势;水对砂岩弹性模量具有弱化作用,不同加载速率下砂岩弹模 的弱化因子变化不大。 ④ 加载速率对砂岩峰后应变的影响较小,饱水砂岩的峰后应变远大 于干燥砂岩,峰后应变的水理强化因子对加载速率不敏感。 ⑤ 砂岩的声发射信号随着加载 速率的增大而增多;相对于干燥砂岩,饱水砂岩的声发射能量累积速度明显推迟,但能量累 积的总量增大3~5 倍。Abstract: Accordingtoasetofuniaxialcompressionexperimentsofsandstone,effectsofdeformation rateandhydratedconditiononthecompressivestrength,elasticmodulus,post-peakstrainandacoustic emission(AE)characteristicswereexplored.Aone-dimensionalconstitutivemodelbyconsideringthe effectsofdeformationrateandhydratedconditionforsandstoneisestablishedandverifiedbydefinings seriesofstrengtheningandweakeningfactors.Theresultsshowthat:①Stress-straincurveofdryrock includeselasticstage,weakplasticstageandbrokenstagewhilethecompactionstage,shorterelastic stageandlongerplasticstageappearforwater-saturatedsandstone.②Deformationrateenlargesthe compressivestrengthofsandstone.Thedeformation-ratefactorofstrengthincreaseswiththeincreasing deformation rate.Water has weakening effect on the compressive strength of sandstone,and the differenceofcompressivestrengthbetweenthedryandsaturatedsandstonedecreasesgraduallywiththe increasingdeformationrate.③Theelasticmodulusofdryandsaturatedsandstoneincreaseslinearly withthedeformationrate.Waterhasweakeningeffectontheelasticmodulus.Theelasticmodulusof saturatedsandstoneislowerthanthatofdrysandstone,andtheweakeningfactorundergoeslittlechange atdifferentdeformationrates.④Deformationratehaslittleeffectonthepost-peakstrainofsandstone, thepost-peakstrainofsaturatedsandstoneismuchhigherthanthatofdrysandstone,andthehydraulic strengtheningfactorofpost-peakstrainisnotsensitivetothedeformationrate.⑤CumulatedAEenergy increaseswithdeformationrate,cumulatedAEenergyadvancesfordryspecimenandpostponesforwater-saturatedstone.Accumulationofenergyforwater-saturatedspecimenis3-5timesthatofdryspecimens.
下载: