复杂巨型滑坡形成机制三维离散元模拟分析

Simulation analysis of formation mechanism of some complex and giant landslides using three-dimensional discrete elements

滑坡位于金沙江下游某拟建的大型水电站库区左岸,距坝址较近,总体积约为2560万m3,属特大型滑坡,其稳定与否将直接威胁到大坝安全和水库正常运营。由于滑坡成因复杂,对其进行合理评价和科学预测尚有困难。为此,结合野外详细勘查资料的分析,对其形成机制进行了定性分析,认为主要以滑移-弯曲型为主,局部可能存在滑移-拉裂或蠕滑-拉裂变形。在此基础上,运用三维离散元数值模拟分析方法,再现了其变形破坏演化过程,进一步证实了其滑移-弯曲型变形破坏机制,很好地解释了主滑带低于现今河床、主滑体南侧边界比较模糊等原因,从而为其发展演化趋势、稳定性和危害性评价提供了有力依据。

The studying landslide locates in the left bank of the reservoir of a planned large-scale hydropower station in Jinsha River; and it is nearby the dam site. Its total volume is about 256 million m^3 and belongs to a giant landslide. So it is stability or not will has a heavy influence on the dam safety and the reservoir normal work. But for its cause of formation is very complex, the rational evaluation and scientific prediction still have difficulty. In order to solve it, combining with the data analysis of detailed investigation and exploration, its qualitative formation mechanism has been analysed. The result thinks that its mechanism is mainly sliding and bending model, and by any possibility some local is sliding and fracturing or creep and fracturing. Based on it, using the numerical analysis method of three-dimensional discrete elements, the evolution process of deformation and destruction has been reappeared; and the genetic formation has been verified further. At the same time, it still has primly explained the reasons of main slip band below the present riverbed, and obscure south borderline of main slide body. The simulation results will provide the powerful foundation to evaluation of development and evolution tendency, stability and harmfulness.