四川甘孜孟底水电站库区坝前堆积体稳定性数值分析

Stability of the deposit located in reservoir area of Mengdi Channel hydroelectric station by numerical simulation

孟底沟沟口右岸堆积体体积高达1500×104m3,其稳定性直接关系到下游孟底电站的建设和运营。研究该堆积体在库水位变化影响下的潜在破坏模式及评价其稳定性对防治工作具有重要的指导意义。本文针对水库蓄水对该堆积体稳定性的影响,在工程地质勘察的基础上,分别采用三维有限差分数值模拟对其稳定性进行了详细的定性分析,并结合二维数值模拟对两条典型剖面的稳定性做出了定量评价。研究结果表明:(1)初始水位时,天然工况下该堆积体基本处于稳定状态;(2)蓄水后稳定性明显恶化,尤其在暴雨的影响下,堆积体极可能沿着基覆界面出现蠕滑变形,引起堆积体发生叠瓦状的后退式破坏。

The deposit in the export of Mengdi channel has up to 1. 5 × 107m3,and its stability is directly related to the downstream adjacent to the construction and operation of a power plant. It has important guiding significance for prevention and control work to study the potential failure modes under the influence of the reservoir water level and to evaluate the stability of the deposit. In order to analysis the stability of the deposit in condition of reservoir storage, based on engineering geological investigation,two methods are respectively taken to have qualitative and quantitative analysis. The method of three-dimensional finite difference is used to qualitatively analysis the deposit's stability,and the method of two-dimensional numerical simulation is used to quantitatively evaluate the stability of the two typical profiles. The results show that in the initial level,the deposit is in a steady state in natural conditions,and then the stability can be deteriorated after reservoir storage. Especially under the influence of heavy rain,the deposit is very likely to produce the creep deformation along the base-cover interface,and then have the imbricate back destruction.