真三轴加卸载岩体各向异性及能量演化机制  

Anisotropy and energy evolution mechanism of rock mass under true triaxial loading-unloading

作　　者：许文松[1,2,3] 赵光明 孟祥瑞[1,2] 刘之喜[1,2] 刘崇岩 戚敏杰 XU Wensong;ZHAO Guangming;MENG Xiangrui;LIU Zhixi;LIU Chongyan;QI Minjie(Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mines,Anhui University of Science and Technology,Huainan232001,China;School of Safety Science and Engineering,Anhui University of Science and Technology,Huainan232001,China;School of Earth Sci-ences and Geomatics Engineering,China University of Mining and Technology-Beijing,Beijing100083,China)

机构地区：[1]安徽理工大学深部煤矿采动响应与灾害防控国家重点实验室,安徽淮南232001 [2]安徽理工大学安全科学与工程学院,安徽淮南232001 [3]中国矿业大学(北京)地球科学与测绘工程学院,北京100083

出　　处：《煤炭学报》2023年第4期1502-1515,共14页Journal of China Coal Society

基　　金：国家自然科学基金资助项目(52004006,51974009);安徽省科技重大专项;安徽省“省特支计划”的领军人才资助项目(T000508)。

摘　　要：地下工程开挖过程中围岩处于极其复杂的应力环境中,尤其是在其各向异性的影响下,动力灾害的发生存在隐蔽性。采用真三轴卸荷扰动岩石测试系统对砂岩进行不同主应力方向加卸载试验,研究真三轴不同主应力加卸载条件下高应力岩体力学特性与破坏特征,分析不同主应力加卸载岩体次生各向异性及能量演化机制。结果表明:(1)在岩体次生各向异性影响下,σ_(1)(第一主应力)进行循环加卸载过程中,ε_(2)(第二主应变)和ε_(3)(第三主应变)呈现相反变化,ε_(V)(体积应变)先压缩再膨胀,最终表现出膨胀的宏观现象;(2)高围压岩体σ_(3)(第三主应力)卸载时,ε_(1)产生压缩,ε_(2)和ε_(3)产生膨胀变形,ε_(2)变化量小于ε_(3),卸荷方向变形由线弹性状态转变为弹-塑非线性;(3)σ_(1)和σ_(3)卸载岩体积聚的能量差异较大,σ_(1)卸载是一个能量释放的过程,σ_(3)卸载是一个能量积聚的过程,卸荷方向的能量变化特征决定了其余2个诱发方向的能量积聚、释放规律,σ_(3)卸载岩体的极限储存能量降低,且σ_(2)(第二主应力)卸荷时随着σ_(1)的增大加快了岩石的破坏,表明岩体卸载比加载更容易破坏;(4)σ_(3)卸荷速度越快,破坏时所释放的能量增加、耗散能降低,卸荷方向岩体能量密度和总积聚能量密度减小。动力事故发生的主要原因是岩体内部能量的积聚释放,岩体次生各向异性对岩体自身极限储存能存在很大影响,研究真三维加卸载次生应力对岩石极限储存能的影响特征为冲击地压防止提供了参考。In the process of underground excavation,the surrounding rock is in a very complex stress environment,especially under the influence of its anisotropy,the occurrence of dynamic disaster is hidden.In this paper,the loading and unloading tests of sandstone in different principal stress directions were carried out by using the true triaxial unloading disturbed rock test system.The mechanical properties and failure characteristics of true triaxial under different principal stresses were studied,the energy evolution mechanism in other directions induced by loading and unloading of different principal stresses was analyzed.Results showed that under the influence of rock mass secondary stress anisotropy,during the cyclic loading and unloading process of the first principal stress,the strain in other directions shows opposite deforma-tion.The volumetric strain compresses first and then expands,and the final volumetric strain shows a macroscopic phe-nomenon of expansion.When the third principal stress of high confining pressure rock mass is unloaded,the first princip-al stress produces a compression deformation,while the second and third principal stresses produce an expansion deforma-tion.The deformation of the second principal stress is less than that of the third principal stress,and the deformation in un-loading direction changes from linear elastic state to elastic-plastic nonlinear state.The accumulated energy of rock mass is a great difference between the first principal stress unloading and the third principal stress unloading.The energy vari-ation characteristics of unloading in the dominant direction determine the energy accumulation and release law in the oth-er two induced directions.The limit stored energy of the third principal stress unloading rock decreases,and the second principal stress accelerates the rock failure with the increase of the first principal stress,which verifies that the rock is easi-er to be destroyed by unloading than by loading.The higher the unloading rate of the third principal stress

关 键 词：真三轴加卸载 各向异性 能量积聚 释放应变能 

分 类 号：TD324[矿业工程—矿井建设]