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

Abstract

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.

Keywords

• large-scale landslide accumulation body
• rainfall
• water level fluctuation
• seepage properties
• stability