地震作用下顺层岩质滑坡启动机制研究  

Study on the initiation mechanism of bedding rock landslide under seismic load

作　　者：赵元平 许明[1,2] 刘先珊 罗斌[3] ZHAO Yuanping;XU Ming;LIU Xianshan;LUO Bin(School of Civil Engineering,Chongqing University,Chongqing 400045,China;National Joint Engineering Research Center of Geologic Hazards Prevention in the Reservoir Areas,Chongqing 400045,China;China Merchants Chongqing Communications Technology Research Design Institute Co.,Ltd.,Chongqing 400067,China)

机构地区：[1]重庆大学土木工程学院,重庆400045 [2]库区环境地质灾害防治国家地方联合工程研究中心,重庆400045 [3]招商局重庆交通科研设计院有限公司,重庆400067

出　　处：《岩石力学与工程学报》2021年第S01期2692-2700,共9页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家自然科学基金资助项目(51779021);广西重点研发计划(2019AB36020);中央高校基本科研业务费(2020CDCGJ021)。

摘　　要：为研究地震作用下顺层岩质滑坡的启动机制,利用断裂力学原理分析滑坡后缘起始裂纹扩展的几何条件和应力条件,推导出最危险起始裂纹角的计算公式,并基于滑坡后缘断裂带完全贯通的条件下,推导在临床弹冲-峰残强降-波动震荡复合效应作用下的滑坡启动速度。研究结果表明,起始裂纹若由次级节理结构面拉裂形成,则次级节理结构面倾角为39.5°的斜坡的起始裂纹最易扩展;滑坡启动经历了后缘起始裂纹累积断裂,后缘断裂带贯通,底部断裂带锁固段瞬间剪断,临床弹冲应变能、峰残强降能释放转化为滑体的初步动能,进一步在波动震荡作用下加速,最终抛离滑坡剪出口的过程。结合“5·12”汶川大地震中青川县东河口滑坡实例分析得出,该滑坡的启动速度受临床弹冲效应影响显著,锁固段剪断瞬间的临床弹冲带条分高度和锁固段长度对启动速度具有决定性控制作用,若不考虑条分高度和锁固段长度的内在联系,在能量转化率为100%时,滑坡启动速度上限为12.5 m/s。To seek the initiation mechanism of bedding rock landslide under seismic load,the geometry and stress conditions of landslide′s initial crack propagation are analyzed and the calculating formula of the most dangerous initial crack angle is deduced by theory of fracture mechanics.Furthermore,based on completely cut-through of landslide′s back fault zone,the starting speed of landslide under the composite effect of elastic impulse,peak-residual strength drop and wave oscillation is derived.The results prove that if initial crack angle starts to break along the secondary joint structural plane,the initial crack of landslides whose dip angle of secondary joint′s structural plane is 39.5°will crack more easily;the landslide′s initiation has experienced a process of cumulative fracture of initial crack,cut-through of landslide′s back fault zone,instantaneous fracture of the locking segment,release of elastic impulse strain energy and peak-residual strength drop strain energy into starting kinetic energy of the slip mass,further accelerated by wave oscillation,and finally being thrown from landslide shear outlet.Based on the analysis of the Qingchuan Donghekou landslide happened in the 5·12 Wenchuan Earthquake,it is concluded that the starting speed of landslide is significantly affected by the elastic impulse effect and decisively controlled by the height of elastic impulse area′s slices and length of locking segment under instantaneous fracture of locking segment,if the internal relationship between height of the slices and length of the locking segment is not considered,the upper limit of landslide′s starting speed will be 12.5 m/s when energy conversion rate reaches 100%.

关 键 词：边坡工程 地震作用 顺层岩质滑坡 启动机制 裂纹扩展 弹冲效应 启动速度 

分 类 号：P64[天文地球—地质矿产勘探]