强震作用下斜坡表面放大效应的三维离散元模拟

为研究强震作用下斜坡表面的动力放大效应, 以陕西勉县某岩质斜坡为例, 建立了三维模型。运用离散元软件3DEC, 模拟了动力条件下斜坡的变形失稳过程, 分析了斜坡表面的动力响应特征, 研究了不同地震波输入工况条件下坡体表面动力响应差异。研究结果表明: 考虑地震纵波的影响时, 竖向加速度得到显著增强, 坡面的PGA放大系数增强了约1.62倍; 坡面形态强烈影响着斜坡表面的动力响应特征, 强震作用下, 斜坡坡肩及坡形转折处的放大效应均十分强烈, 凸出部位次之, 坡表两侧的放大效应最弱; 不同输入工况下, 斜坡坡形转折处的水平向PGA放大系数均维持较高值, 特别是在仅输入水平向加速度的条件下, 该部位在地震滑坡灾害预防中应特别注意; 强震作用下滑坡的运动过程可概括为滑坡孕育启动阶段—挤压碰撞高速运动阶段—堆积阶段。研究成果可为该地区防灾减灾工作提供一定理论支持。 

Three-dimensional discrete element simulation of the amplification effect of the slope surface under the action of strong earthquakes

To study the dynamic amplification effect of slope surfaces under the action of strong earthquakes, a three-dimensional model was established using a rocky slope in Mian County, Shaanxi Province, as an example. The discrete element software 3DEC is used to simulate the deformation and instability process of the slope under dynamic conditions, analyse the dynamic response characteristics of the slope surface, and study the difference in the dynamic response of the slope surface under different seismic wave input conditions. The main conclusions are that when considering the influence of seismic longitudinal waves, the vertical acceleration is significantly enhanced, and the PGA amplification factor of the slope is increased by approximately 1.62 times. The slope shape strongly affects the dynamic response characteristics of the slope surface. Under the action of strong earthquakes, the amplification of the slope shoulder and the slope turning point is very strong, followed by the protruding parts, and the amplification on both sides of the slope surface is the weakest. Under different input conditions, the horizontal PGA amplification factor at the slope turning point maintains a high value, especially when only the horizontal acceleration is input, and this part should be given special attention in the prevention of earthquake landslide disasters. The movement process of a landslide caused by strong earthquakes can be summarized as the initiation stage of the landslide-the high-speed movement stage of the squeeze collision-the accumulation stage. The research results can provide certain theoretical support for disaster prevention and mitigation in this region.