尼续高速远程滑坡形成机制及运动过程模拟研究

Study on Formation Mechanism and Motion Process Simulation of Nixu Rapid and Long-runout Landslide

以青藏高原东南部西藏自治区拉萨市尼木县续迈乡尼续村的尼续高速远程滑坡为研究对象,根据详细的地质调查初步判断其形成机制,并采用基于有限差分法的三维计算模型对尼续高速远程滑坡的运动过程进行了模拟研究。研究结果表明:尼续高速远程滑坡的主要形成机制为经地震触发启动,失稳块体在流通区撞击解体,并侵蚀裹挟坡前粗砂继续运动,到达河谷阶地后滑体对下覆饱和砂层的加载、剪切所引起的滑带土液化;尼续高速远程滑坡运动过程历时约215 s,最大平均速度可达34 m/s,其速度整体呈“急剧加速-持续减速”趋势;模拟所得的滑距、速度、堆积范围及厚度与现场调查结果吻合度较高,同时证实了高液化程度对滑坡有着明显的促滑作用。该结论可为类似地区高速远程滑坡运动的研究提供参考。

Based on the Nixu rapid and long-runout landslide in Nixu Village,Xumai Township,Nimu County,Lhasa City,Tibet Autonomous Region,the formation mechanism was preliminarily determined by detailed geological survey.The motion process of the Nixu landslide was simulated by the 3D calculation model based on the finite difference method.The results show that the unstable block disintegrated in the transportation zone after seismic triggering,and the broken block was impacted to breakup in the circulation area to wrap the coarse sand before the slope to move on.After reaching the valley terrace,the liquefaction caused by the loading and shearing of the overlying saturated sand layer by the sliding body is the main formation mechanism of the Nixu rapid and long-runout landslide;The duration is approximately 215 seconds with a maximum average speed of 34 m/s.The overall speed shows a trend of“sharp acceleration-continuous deceleration”.The simulated slip distance,velocity,accumulation range and thickness align well with field survey results,confirming that high liquefaction significantly promotes landslide movement.This conclusion can provide reference for studying high-speed and long-distance landslide movement in similar areas.