苗尾水电站赵子坪岸坡变形失稳的地下水动力作用分析

库水位变动是诱发库岸边坡变形失稳的主要因素。为探究库水位变动下倾倒变形岩体破坏后形成的堆积体斜坡的地下水动力作用，以云南澜沧江的苗尾水电站赵子坪滑坡为研究对象，通过现场地质调查和勘探确定了滑坡形态和坡体结构特征；再结合监测数据深入分析了滑坡在地下水动力作用下的变形失稳机制，并基于非饱和土力学理论和有限元法对其失稳机制进行进一步验证。结果显示:赵子坪岸坡为原始倾倒岩体变形破坏后上部强倾倒岩体沿着折断面发生滑动而形成的堆积体斜坡，内部呈层状堆积的片石表明其还保留了部分倾倒岩体的结构特征。水库蓄水后，由于松散的倾倒堆积体为库水渗入坡体创造了良好的条件，地下水位随库水位升高而快速升高，导致孔隙水压力增大而滑坡阻滑段有效应力减小，从而造成稳定性降低，滑坡易沿着由倾倒折断面演化而成的基覆界面发生滑动破坏。

Dynamic analyses of groundwater on the deformation and instability of the Zhaoziping bank slope near the Miaowei Hydropower Station

Variation in reservoir water level is the main factor inducing the deformation and instability of bank slopes. In order to explore the groundwater dynamic effect of the slope formed by the collapse of toppling deformed rock mass under the change in reservoir water level, the Zhaoziping landslide near the Miaowei Hydropower Station on the Lancangjiang River in Yunnan was taken as the research object, and the landslide morphology and structure characteristics were determined by field geological survey and exploration. The deformation and instability mechanism of the landslide under the action of groundwater dynamic was analyzed in detail using the deformation monitoring data. They are validated based on the unsaturated soil mechanics theory and finite element method. The results show that the Zhaoziping bank slope is an accumulation slope formed by the sliding of the upper strongly toppled rock mass along the fracture surface after the deformation and failure of the original toppled rock mass. The stratified accumulation of schistose rock in the slope indicates that it retains some structural characteristics of toppled rock mass. After the reservoir impoundment, because the loose toppling accumulation body creates good conditions for reservoir water to infiltrate into the slope, the groundwater level rises rapidly with the reservoir water level rising, which leads to the increase in pore water pressure and the decrease in effective stress in the landslide resistance section, thus the stability of the landslide decreases, and the landslide is liable to slide along the bedrock cover interface evolved from the fracture surface.