大型厚层崩滑体运动特征模拟研究:以重庆武隆县羊角场镇大巷危岩为例

Run-out prediction of large thick-bedded unstable rock:A case study of Daxiang unstable rock in Yangjiao town,Wulong county,Chongqing

高速远程滑坡-碎屑流是大型危岩体失稳破坏的主要成灾模式之一,它具有启动速度快、运动距离远、覆盖范围广的特点,具有极强破坏性,预测分析大型危岩体的运动特征具有重要的研究意义。文中选取重庆武隆县羊角场镇大巷危岩为研究对象,通过调查危岩体所处的地质地貌条件和危岩体发育特征,分析总结其潜在失稳模式和失稳后运动过程,利用DAN3D动力分析软件,参考鸡尾山滑坡反演分析的流变模型和参数,对危岩失稳后形成滑坡-碎屑流的运动学特征进行预测分析。模拟结果表明:(1)大巷危岩失稳后运动过程可分为启动、偏转抛出、碰撞铲刮和远程堆积4个阶段,运动时间约为220s,形成滑坡-碎屑流的滑程为2 500m;(2)大巷危岩滑体方量530×104 m3,滑后堆积体方量790×104 m3,堆积体水平长约1 680m,平均厚度约为6m,铲刮最大厚度为8m,碎屑流运动过程中最大速度为60m/s;(3)碎屑流可穿过羊角场镇城区抵达乌江,说明羊角场镇城区在大巷危岩的危害范围内;(4)文中的模拟计算结果可为高速远程滑坡-碎屑流的危险性定量评价研究提供依据。

High-speed long run-out landslide-debris flow is one of the most destructive failure modes of large unstable rock,which can be fast launching,run long distance and cover large area,so the run-out prediction research of large unstable rock has great practical significance.Taking the Daxiang unstable rock as a study case,this project aimed at predicting the dynamic characteristics of long run-out landslide-debris flow.Based on geological and geomorphological survey,the development characteristics and failure pattern of Daxiang unstable rock were analyzed.The DAN3 Dcode and the rheological parameters calibrated through the inversion analysis of Jiweishan landslide were used for the analysis of the Daxiang unstable slope.The simulation results show that（1）the movement process of rockslide-debris avalanche could be divided into four stages as launching,deflection and throwing,crash and erosion,and long range accumulation.The whole process took220 s,and travel distance was 2500m;（2）the volume of the sliding mass was 530×104 m3,the total volume of the accumulation was 790×104 m3,the length of the accumulation was 1680 mand average depth was 6m,the maximum erosion depth along the path was 8m,and the maximum velocity was 60m/s;（3）the debris could go though Yangjiao Town and reach the Wujiang River,which implies that the Yangjiao Town is in the danger zone;and（4）the simulated prediction could be used as a reference for landslide hazard quantitative assessment.