强震荷载下裂缝岩体拉剪破坏机理  

FAILURE MECHANISM OF DANGEROUS ROCK UNDER SEISMIC TENSION-SHEAR ACTION

作　　者：何思明[1,2] 吴永[1,2] 李新坡[1,2] 

机构地区：[1]中国科学院山地灾害与地表过程重点实验室,四川成都610041 [2]中国科学院水利部成都山地灾害与环境研究所,四川成都610041

出　　处：《工程力学》2012年第4期178-184,共7页Engineering Mechanics

基　　金：科技支撑计划项目(2011BAK12B03);国家自然科学基金项目(40872181);交通部西部科技项目(2006-318-792-85)

摘　　要：崩塌是地震诱发的最严重次生地质灾害之一,但目前有关地震崩塌的力学机理还不清晰。为此,基于天然危岩体的宏观结构特征,从岩石断裂力学的角度入手,对比分析了不同震波模式下裂缝的失稳扩展条件,确立了拉剪破坏的危岩失稳机制;继而以能量法为手段,研究了震波能量在危岩体中的输入和耗散机制,解析拉剪条件下裂缝的扩展方向和危岩失稳机理,给出裂缝扩展的加速度临界值ac和扩展量的计算方法;最后,通过具体算例验证了模型的合理性;结果显示,震时危岩体的失稳是裂缝在拉剪震波作用下沿震波入射垂直方向间断扩展累积的结果。As one of the most serious hazards in an earthquake,the collapse is very hard to control largely because the failure mechanism of rock slope is not clearly addressed.Here from the view of Fracture Mechanics and based on the structural characters of natural dangerous rock,the propagation condition of cracks under different seismic waves was analyzed contrastively,and it is found that the tension-shear failure of cracks is the main mode of collapse in an earthquake.Then the energy method was taken as a main way to study the crack propagation direction and rock failure mechanism.The paper proposed approaches to calculate the crack growth amount and critical seismic acceleration,which result in crack failure.Finally,an example was given to validate the theory.The result shows the failure of dangerous rock in earthquake is mainly caused by the discontinuous propagation and continuous accumulation of cracks under tension-shear action of seismic action and along the vertical direction of seismic force.

关 键 词：地震波 裂缝扩展 临界加速度 Griffith理论 拉剪破坏 

分 类 号：TU457[建筑科学—岩土工程]