基于损伤演化的砂岩能量参数围压效应研究

岩石材料损伤演化状态所对应的特征参数,对岩土工程的稳定性设计、预测及监测等至 关重要。 本文开展不同围压下砂岩分级循环加卸载试验,利用横向应变法和体积应变法确定受 载岩样损伤演化状态,基于损伤演化状态分析各阶段、各损伤演化特征点处能量参数演化特征及 与围压的关系。 结果表明:不同围压下,峰前各阶段能量参数随应变增大而增大;随着围压的增 大,峰值应力处的弹性应变能、耗散能突变向峰后转移;峰后残余应力阶段各能量参数降低并趋 于平缓。 σcc 处能量参数与围压成幂函数下降关系,且耗散能随围压增大趋于稳定;σci、σcd 及 σp 处能量参数随围压呈线性增加,各特征点处输入能量与弹性应变能差值随围压的变化趋势较小, 且在 σcd 处两者相对差值最小,输入能量转化为弹性应变能最多。

Confining pressure effect on energy parameters of sandstones based on damage evolution

Thecharacteristicparameterscorrespondingtodamageevolutionstateofrockmaterialarecrucialtodesigning,predictingandmonitoringthestabilityofgeotechnicalengineering.Thecyclicloadingunloadingtriaxialcompressiontestsofsandstoneswereimplementedwithdifferentconfiningpressure,and thedamage evolution state were determined by the lateral strain method and the volumetric strain method,andtheenergyparametersphasedevolution,theenergyevolutionofcharacteristicpointscorrespondingtodamageevolutionstateandrelationwithconfiningpressure,wereanalyzedbasedondamage evolutionstate.Theresultshowedthat:withdifferentconfiningpressure,theenergyparametersincreased withtheincreaseofthestrainateachstagebeforethepre-peak;themutationoftheelasticstrainenergy andthedissipationenergyatpeakstresstransferredtopost-peakwiththeincreaseoftheconfiningpressure;theenergyparametersdecreasedtoleveloffatresidualstressstage.Theenergyparametershada powerfunctiondecreasewithconfiningpressureatthepointofσcc,andthedissipationenergydecreased?toleveloffwiththeincreaseoftheconfiningpressure.Atthepointsofσci,σcdandσp,theenergyparametersincreasedlinearlywithconfiningpressure,andtherewassmallchangetrendofthedifferencebetweenthetotalinputenergyandtheelasticstrainenergywiththeconfiningpressureatthedifferentcharacteristicpoints,andtherelativedifferencebetweenthetotalinputenergyandtheelasticstrainenergywas minimum,andthetotalinputenergyconvertedintotheelasticstrainenergywasmaximumatpointσcd.