三峡库区碎石土质岸坡失稳启动机制研究——以龙江红岩子滑坡为例

三峡水库蓄水后,滑坡成为三峡库区最严重的地质灾害之一,库水位下降和降雨是导致滑坡的重要因素。以龙江红岩子滑坡为例,研究三峡库区碎石土质岸坡失稳启动机制。基于FLAC^3D渗流分析模块功能和算法对三峡库区龙江红岩子滑坡的机制进行研究。根据龙江红岩子岸坡的地形、地质条件,建立了龙江红岩子滑坡渗流模拟有限差分计算模型,并确定了模型合理的水头边界条件。通过编写内置的FISH函数对降雨入渗、不同库水位等工况进行模拟,得到了位移场的变化规律,分析了不同库水位及降雨条件下碎石土质岸坡的稳定性,揭示了岸坡在降雨和水位下降过程中的稳定性衰减过程。降雨和水位骤降的共同作用是龙江红岩子滑坡的触发因素。为研究不同库水位和降雨条件下碎石土质库岸滑坡稳定性提供了依据。

Instability initiation mechanism of gravel soil slope in Three Gorges Reservoir: case study of Hongyanzi landslide in Wushan county

After impoundment of the Three Gorges Reservoir, landslides have become one of the most serious geological hazards in this area. These landslides are mainly caused by the declining water levels and rainfall. Taking Hongyanzi landslide in Wushan county as an example, the collapsing initiation mechanism of bank slope combined debris and soil in the areas of Three Gorges Reservoir are studied. Based on the function and algorithm of FLAC^3D seepage analysis module, the mechanism of Hongyanzi landslide is investigated. According to the topographical and geological conditions of Hongyanzi bank slope, the construction of seepage simulation of Hongyanzi landslide is realized by using the finite difference method, and reasonable condition of hydraulic head boundary is confirmed for this model. The change rules of the displacement field are drawn by simulating rainfall infiltration and different water level conditions by writing the built-in FISH function. The stability of bank slope combined debris and soil is analyzed under different water level and rainfall conditions. And the declining stability of bank slope is revealed in the process of rainfall and the declining water levels. The triggering factor of Hongyanzi landslide is the combined effects of rainfall and drawdown of water level. These research results provide a basis for studying the stability of debris and soil bank landslides with different reservoir water level and rainfall conditions.