基于流形元模型的高速远程滑坡碎屑流运动规律与拦挡结构减灾效果研究

高速远程滑坡碎屑流具有极高的动能和超远移动距离，是一种危害范围广、破坏力极大的地质灾害。目前研究多基于高速远程滑坡的效应机理，对于拦挡结构减灾作用研究较少，尚未形成完善的高速远程滑坡减灾体系，而数值模拟是研究碎屑流拦挡结构减灾作用的重要手段。本文采用数值流形方法对牛圈沟强震诱发滑坡所形成的高速碎屑流运动过程进行了模拟，分析其堆积状态以及运动特性，通过数值试验研究了碎屑流运动路径上植被覆盖、拦挡墙高度、位置以及布置方式对高速远程滑坡碎屑流堆积状态的影响，并对拦挡墙的减灾作用进行评价。不同于颗粒离散元方法，数值流形方法可以模拟任意形状块体相互接触、碰撞，从而避免了运动过程中圆颗粒滚动摩擦对模拟结果的影响。模拟结果表明，尽管在碎屑流运动路径上增加植被覆盖可降低碎屑流运动距离，为达到更好拦截碎屑流的效果，仍需在运动路径上布置拦挡墙，以有效降低碎屑流的沿程位移及远程堆积量。当拦挡墙布置于不同位置时，对滑坡碎屑流有不同的截流阻滑作用，并确定拦挡墙的最优位置。此外，相对于增加拦挡墙高度，设置多排拦挡墙可更加有效地拦截碎屑流以减少对下游的危害。

Simulation of Movement of High-speed and Long Run-out Landslide Rock Avalanche and the Disaster Reduction Effects of Retaining-wall Based on the Numerical Manifold Modelling

The high-speed and long run-out landslide is characterized by high kinetic energy and long moving distance, which leads to enormous loss to human beings. However, there are rare investigations on the disaster reduction effects of retaining-wall structure on high-speed and long run-out landslide rock avalanche. Numerical simulation provides an important method to study the effects. In this paper, the numerical manifold method was used to simulate the movement process of high-speed and long run-out landslide rock avalanche induced by strong earthquake in Niuquangou, China. The accumulation state and movement characteristics of the landslide were studied through a series of numerical tests. The effects of vegetation coverage, retaining-wall on it accumulation state of rock avalanche were studied, and the disaster reduction effects of retaining-wall was evaluated. Compared with the discrete element method, the numerical manifold method can simulate the contact and collision of any shape blocks, avoiding the impact of rolling friction of round particles on the simulation results during motion. The simulation results showed that the effects of increasing vegetation coverage on the landslide movement path is limited. In order to intercept rock avalanche better, retaining-wall needs to be arranged on the motion path to effectively reduce moving distance and long-distance accumulation of rock avalanche. When the retaining-wall is placed in different positions,it has defferent effect on the landslide rock avalanche,and the optimal position of the retaining-wall is determined. In addition, compared with effects of increasing the height of the retaining-wall, the multiple rows of retaining-wall structure can more effectively intercept the rock avalanche and reduce it harm to downstream.