摘要
为探究围压对受载岩样能量演化特征的影响规律,设计了按轴向位移等梯度加载的恒围压卸轴压的试验应力路径,采用MTS815岩石力学试验系统开展了6种围压下岩样的三轴循环加卸载试验;提出基于加卸载曲线的面积来计算岩石能量的方法,避免采用弹性模量不变的假设而造成能量计算误差,采用特征能量密度和能耗比参数来表征受载岩样的能量积聚、耗散及释放行为,揭示了受载岩样能量演化过程及分配规律的围压效应。试验结果表明:随着从峰前向峰后阶段推移,弹性能占比逐渐降低,耗散能占比逐渐提高,在残余阶段能量占比趋于稳定。随着围压的提高,岩样的特征能量密度随之增大。能耗比(耗散能密度与弹性能密度的比值)可表征受载岩样内部损伤积累状态,在峰前阶段,能耗比随循环次数的增加而增大;在峰后阶段,能耗比先增大后减小,出现拐点(受载岩样大面积破裂或破坏的征兆点)。围压可抑制因岩样破裂或破坏时能量的耗散和释放,造成岩样破坏时所释放的弹性能不彻底;随着围压的提高,能耗比随之降低。
To explore the influence of the confining pressure on energy evolution characteristics of loaded rock samples,the experimental stress path of constant confining pressure and unloading axial pressure is designed by applying a constant axial displacement increment at the same time interval,and triaxial cyclic loading and unloading tests under six confining pressures are carried out using the MTS815 rock mechanics test system.A method for calculating rock energy based on the area formed by the loading and unloading curves is proposed,which avoids the energy calculation error caused by the assumption of constant elastic modulus.The characteristic energy density and energy consumption ratio are adopted to define the energy accumulation,dissipation and release behaviors of loaded rock samples,and the confining pressure effects of the energy evolution process and energy distribution law of the loaded rock sample are revealed.The test results show that with the passage from the pre-peak to the post-peak,the elastic energy ratio gradually decreases,whereas the proportion of the dissipated energy gradually increases.The proportions of both elastic and dissipated energies tend to be stable in the residual phase.The characteristic energy density of rock samples also increases with the increment of confining pressure.The energy consumption ratio,which is defined as the ratio of the dissipated energy density to the elastic energy density,can characterize the internal damage accumulation state of the loaded rock samples.In the pre-peak stage,the energy consumption ratio undergoes a change from increasing to decreasing,and there is an inflection point that corresponds to the symptom point of large-scale cracking or destruction of the loaded rock samples.The confining pressure can suppress energy dissipation and release due to the fracture or failure of rock samples,resulting in incomplete release of the elastic energy when the rock sample is damaged,and the energy consumption ratio is negatively correlated with the confining pre
作者
孟庆彬
王从凯
黄炳香
浦海
张志镇
孙稳
王杰
MENG Qingbin;WANG Congkai;HUANG Bingxiang;PU Hai;ZHANG Zhizhen;SUN Wen;WANG Jie(State Key Laboratory for Geomechanics add Deep Underground Engineering,China University of Mining and Technology,Xuzhou,Jiangsu 221116,China;State Key Laboratory of Coal Resources and Safe Mining,China University of Mining and Technology,Xuzhou,Jiangsu 221116,China)
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2020年第10期2047-2059,共13页
Chinese Journal of Rock Mechanics and Engineering
基金
国家自然科学基金资助项目(51704280)
中国博士后科学基金项目(2015M580493,2017T100420)。
关键词
岩石力学
三轴循环加卸载试验
能量演化特征
能量分配规律
能耗比
围压效应
rock mechanics
triaxial cyclic loading and unloading test
energy evolution characteristics
energy distribution law
energy consumption ratio
confining pressure effect
