库水位升降与降雨作用下大型滑坡体渗流稳定性分析

库岸滑坡体分布广泛，在库水位升降和降雨条件下极易失稳。三板溪水电站东岭信滑坡堆积体总方量2 000×104 m3，最大厚度150 m，2006年水电站蓄水后滑坡体开始出现大变形，每年雨季加剧。首先经野外地质勘察和十余年监测数据整理，探明了地质条件和变形规律；其次使用SEEP/W模块对不同库水位升降速率、2019年库水位结合实测降雨条件下的饱和-非饱和流进行模拟，并采用SLOPE/W分别计算不同时刻的稳定系数。分析认为东岭信为超深层滑坡，其变形过程深受库水位升降和降雨影响；滑坡体具有明显的滞水特征，渗流过程复杂；在库水位上升过程中稳定系数不断下降，而在库水位消落过程中稳定性逐渐增强；在库水位上升和强降雨量共同作用下稳定性下降很快，汛后10 d左右达到最低值，此时的稳定性最差。本研究可用于指导库水位升降和降雨条件下大型滑坡体稳定性评价。 

Analysis of seepage stability of large-scale landslide under water-level fluctuation and rainfall

Landslide is widely distributed on the bank of the reservoir, which is easy to cause instability under the condition of water level fluctuation and rainfall.Donglingxin landslide accumulation body of the Sanbanxi Hydropower Station has a maximum thickness of 150 m and a total volume of 2 000×104 m3.The slope began to show large deformation at the first impoundment of the hydropower station in 2006, and the deformation is accelerated at the annual rainy season.Firstly, based on the field geological investigation and over ten years of monitoring data, the geological conditions and deformation law of the landslide body were obtained.Secondly, the saturated-unsaturated flow was calculated with different reservoir water levels fluctuation rates and the measured reservoir water level together with rainfall in 2019 by SEEP/W, and SLOPE/W was used to calculate the stability factors at different time.Results show that the slope is a super-deep landslide, which deformation process was deeply affected by the rise and fall of the reservoir water level and rainfall; The slope has characteristics of stagnant water, and the seepage process is complex; The stability coefficient decreases continuously in the process of reservoir water level rising while increases gradually in the process of reservoir water level falling; The stability declines rapidly with the combined effect of rising reservoir water level and heavy rainfall, and reaches the lowest value about 10 days after the flood season.The research can be used to guide the stability evaluation of large-scale landslide under water-level fluctuation and rainfall.