真三轴应力路径花岗岩卸荷破坏力学特性研究  

Research on the mechanical characteristics of granite failure process under true triaxial stress path

作　　者：刘婕 张黎明[1,2] 丛宇[1,2] 王在泉[1,2] LIU Jie;ZHANG Li-ming;CONG Yu;WANG Zai-quan(School of Science,Qingdao University of Technology,Qingdao,Shandong 266033,China;Cooperative Innovation Center of Engineering Construction and Safety in Shandong Blue Economic Zone,Qingdao University of Technology,Qingdao,Shandong 266033,China)

机构地区：[1]青岛理工大学理学院,山东青岛266033 [2]青岛理工大学蓝色经济区工程建设与安全协同创新中心,山东青岛266033

出　　处：《岩土力学》2021年第8期2069-2077,共9页Rock and Soil Mechanics

基　　金：国家自然科学基金(No.41702322);山东省自然科学基金(No.ZR2020ME099,No.ZR2020MD111)。

摘　　要：开展某洞库花岗岩真三轴加载破坏试验和卸载破坏试验,分析花岗岩的特征应力、破坏形式和能量演化特征。试验结果表明:真三轴加、卸荷应力路径下,花岗岩的破坏方式均为张剪复合破坏,表现出高损伤应力特征和明显的脆性特征;利用体积应变曲线提出新的脆性指数评价岩石脆性,发现卸荷条件下花岗岩的脆性指数更高;真三轴加荷试验中,总能量-轴向应变曲线经历缓慢增大、快速增大、稳定增大3个阶段;真三轴卸荷试验中,卸荷瞬间耗散能迅速增加,在能量分配中所占的比例迅速提高,成为消耗能量的主体;加荷试验中花岗岩破坏时的耗散能量值明显大于卸荷试验,表明加荷路径下需要消耗更多的能量才能发生破坏,且卸荷路径下可释放弹性应变能多,相较于加荷路径更加危险。The true triaxial loading and unloading tests were conducted to obtain the characteristic stress,failure mode and energy evolution characteristics of the granite in an underground cavern.Results show that under the true triaxial loading and unloading stress paths,the failure modes of granite are both tensile and shear composite failure,and characteristics of high damage stress and brittleness are obviously observed.A new brittleness index is proposed to evaluate rock brittleness by using volumetric strain curve.The brittleness of granite under unloading condition is higher than loading condition.In the true triaxial loading test,the change trend of total energy with axial strain goes through three stages:slow increase,rapid increase,and steady increase.In the true triaxial unloading test,the dissipated energy increases rapidly at the moment of unloading,and its proportion in the energy distribution increases,which becomes the main energy consumption.The energy dissipation value of the granite in the loading test is obviously greater than that in the unloading test.It indicates that more energy is required for samples under the loading path to cause damage.More elastic strain energy can be released under the unloading path,which is more dangerous than the loading path.

关 键 词：真三轴试验 力学特性 能量演化 

分 类 号：TU452[建筑科学—岩土工程]