三轴循环荷载作用下页岩能量演化规律及强度失效判据研究  

Variation of energy and criteria for strength failure of shale under traixial cyclic loading

作　　者：李子运 吴光[1] 黄天柱 刘洋 

机构地区：[1]西南交通大学地球科学与环境工程学院,四川成都611756 [2]重庆科技学院建筑工程学院,重庆401331

出　　处：《岩石力学与工程学报》2018年第3期662-670,共9页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家自然科学基金资助项目(41302223);重庆市国土资源和房屋管理局科技计划项目(KJ–2015 047);重庆市教育委员会科学技术研究项目(KJ1713327)~~

摘　　要：基于不同围压下三轴循环加、卸载试验和能量原理,研究页岩吸收轴向应变能1U、积聚和释放可释放弹性应变能eU、塑性变形及裂隙扩展消耗损耗能dU和径向膨胀变形消耗径向扩散能3U的能量转化全过程特征,揭示其受载过程的能量演化规律,建立基于能量突变的岩石强度失效判据。研究成果表明:不同围压下的页岩三轴循环加、卸载全过程,能量演化行为相似,体现为峰前以能量积聚为主,破坏过程发生能量释放和能量耗散,峰后残余强度下重新开始积聚能量,但能量积聚能力和效率不如峰前。岩石破坏阶段,可释放弹性应变能eU沿主裂隙大量释放,破裂岩块沿主裂隙发生位移和摩擦,消耗大量损耗能dU,径向应变3?显著增大,径向扩散能3U大幅增长。与峰前相比,峰后残余强度阶段可释放弹性应变能eU和损耗能dU的量值水平大幅下降但总体保持平稳,径向扩散能3U显著增加。围压对峰前各能量参数的分配比例影响不大,对峰后残余强度下岩石的能量积聚能力有一定提升作用。页岩和红砂岩的弹性能耗比K在峰前阶段随轴向应变的增加缓慢减小,期间变化平稳,在岩样发生强度失效时,拐点出现,增长速度突然增大,产生突变。The whole process of strain energy conversion of shale in absorbing the axial strain energy1 U,storing and releasing the elastic strain energy Ue, dissipating the energy Ud for plastic deformation and cracks propagation,expending strain energy3 U for circumferential deformation was studied based on the energy theory and the shale tests under traixial cyclic loading. The variation of shale energy was revealed,and the criteria for strength failure of shale was established based on the energy catastrophe. The variation of behavior of shale specimen under the different confining pressures in the test of traixial cyclic loading was found to be similar and dominated by the energy accumulation before the peak stress,then the energy dissipation and releasing were predominant in the failure stage after the peak stress,the energy accumulation restarted after the shale specimen reached its residual strength,but its efficiency and capability was inferior to those before peak stress. In the failure stage,the elastic strain energy Ue was released in large quantities along the main fracture,the dissipating energydU was consumed largely when the fractured rock mass frictionally slid along the main fracture,and the expending strain energy3 U grew substantially with the radial strain. Comparing with that before the peak stress,the magnitude of the elastic strain energy Ue and the dissipating energydU in the stage of residual strength decreased substantially but have maintained stable while the expending strain energy3 U increased a lot. The confining pressure did not affect much the energy ratio in the stage before the peak stress,but enhanced the efficiency and capbility of energy accumulation in the stage of residual strength. In the stage before the peak stress,the consumption ratio of elastic energy of shale and red sandstone decreased slowly with the axial strain,its changing rate went smoothly. In the failure stage,the inflection point of the elastic energy consumption ratio appears with a significant increasing in magnitude

关 键 词：岩石力学 三轴压缩 能量演化 能量突变 强度失效判据 

分 类 号：TU45[建筑科学—岩土工程]