强震条件下西藏则隆弄沟高位滑坡失稳特征研究  

Study on the unstable characteristics of high-level landslide in Zelongnong gou,Xizang under severe earthquakes

作　　者：刘俊辰 王文沛 高杨[3,4] 万佳威 高少华 LIU Junchen;WANG Wenpei;GAO Yang;WAN Jiawei;GAO Shaohua(School of Engineering and Technology,China University of Geosciences,Beijing 100083,China;China Institute of Geo-Environment Monitoring(Guide Center of Prevention Technology for Geo-Hazards,MNR),Beijing 100081,China;Institute of Geomechanics,Chinese Academy of Geological Sciences,Beijing 100081,China;Key Laboratory of Active Tectonics and Geological Safety,Ministry of Natural Resources,Beijing 100081,China)

机构地区：[1]中国地质大学(北京)工程技术学院,北京100083 [2]中国地质环境监测院(自然资源部地质灾害技术指导中心),北京100081 [3]中国地质科学院力学研究所,北京100081 [4]自然资源部活动构造与地质安全重点实验室,北京100081

出　　处：《中国地质灾害与防治学报》2024年第6期15-23,共9页The Chinese Journal of Geological Hazard and Control

基　　金：国家重点研发计划项目(2022YFC3004301)。

摘　　要：西藏则隆弄沟物源位置高、强度低,历史上因强震失稳后发生过崩滑。为探究强震对1950年则隆弄沟的动力响应特征,文章采用FLAC3D的动力模拟方法进行演算,并输入双向米林地震加速度记录。结果表明:其动力响应较复杂,受控于坡体形态、材质、地震波强度和频率等因素,在靠近海拔4000 m处冰碛物出现挤压破裂,而不是位于最前端的冰碛物前缘;在海拔5500 m时冰碛物与花岗片麻岩之间的切应变增量达到最大,远高于冰碛物后缘;该斜坡存在一条滑面且已经贯通,范围为海拔4000~5800 m,失稳类型为拉-剪。为进一步分析造成这种失稳形态的影响因素,引入共振的概念,使用公式计算及不同频率简谐波激励,得到该坡的固有频率处于0.09~1.89 Hz之间,其中4400~5500 m固有频率为0.2~0.6 Hz。而加速度放大效应受固有频率的影响,地震波主频与坡体海拔4400~5500 m固有频率重合度较高,产生同频共振现象,放大效应明显。通过分析,地震波在不同材质中的放大效应不同,冰碛物放大效应弱于花岗片麻岩。The Zhelonglnong gou landslide in Xizang,located at high elevation with low intensity,has historically experienced significant instability due to strong earthquakes.To explore the dynamic response of the 1950 landslide to seismic events,this study employs FLAC3D dynamic simulations and bi-directional Milin earthquake acceleration records.The results show that the dynamic response is complex,influenced by slope geometry,material properties,and seismic wave intensity and frequency.At an elevation of 4000 m,glacial deposits exhibit compressive failure rather than failure at their leading edge.At 5500 m,the shear strain increment between glacial deposits and gneissic schist reaches its maximum,significantly higher than at the trailing edge of the glacial deposits.A sliding surface is identified between 4000 m and 5800 m,with a pull-and-shear failure type.To further analyze this instability pattern,resonance is considered,and the slope's natural frequency is found to range from 0.09 Hz to 1.89 Hz,with values of 0.2 Hz to 0.6 Hz between 4400 m and 5500 m.The seismic wave frequency closely matches the slope’s natural frequency in this range,resulting in significant resonance amplification.The amplification effect is stronger in gneissic schist than in glacial deposits.

关 键 词：高位滑坡 放大效应 固有频率 同频共振 

分 类 号：P642.22[天文地球—工程地质学]