地震作用下顺层岩质滑坡稳定性离散元模拟

以金沙江溪洛渡水电站库区恩子坪2#滑坡为例,采用宁河地震天津记录数据作为地震动参数,运用离散元程序UDEC(Universal Distinct Element Code)对滑坡在未来地震作用下的响应特征和变形破坏机制进行数值模拟。数值模拟计算结果显示:在地震波作用下,坡体表现出明显的放大效应,其中加速度放大程度最大,位移次之,速度最小;地震波达到峰值后,坡体中的剪应力集中范围和滑带的剪应变均急剧增大,由于剪应变累积效应,变形破坏从滑带前端向尾部传递、扩展;地震结束时,滑坡的稳定性系数已经低于1.0,最大累积位移达到了1.58 m。通过分析数值模拟计算结果可知:运动放大效应、剪应力集中和剪应变累积效应是导致滑坡变形破坏的主要机制,滑坡的失稳模式依然为顺层滑移;滑坡已经失稳破坏,建议采取适当的锚固工程,以降低滑坡在地震作用下失稳堵江的风险,从而保证溪洛渡水库的正常运营。

Discrete Element Simulation of Stability of Bedding Rocky Landslide Under Earthquake Action

In this research, we simulate the dynamic response characters and failure mechanism of landslide by u?sing the universal distinct element code( UDEC) . Enziping landslide No. 2 in the Xiluodu reservoir area of Jinsha river is taken as example, and Ninghe?Tianjin earthquake record as the dynamic parameter. Simulated results show that:1) under earthquake action, slope shows obvious amplification effect, and amplification effect of acceleration is the biggest, followed by displacement, velocity;2) area of shear stress concentration and the shear strain of the slip zone dramatically increase after the peak value of the seismic wave, and the deformation and failure extended from the front to the rear of the slip zone due to the accumulation effect of shear strain;3) safety factor of landslide stability is less than 1.0 and the maximum accumulated displacement is up to 1.58 m when the earthquake stops. Through analyzing calculated data, we conclude that failure mechanism of the landslide results from the combination effect of motion amplification and shear stress concentration and the accumulation of shear strain, and the failure mode remains bedding slide. In light of failure state of the landslide, we give suitable anchoring treatment sugges?tions for reducing the risk of river closure by earthquake?induced landslide so as to ensure the operation of Xiluodu hydropower project.