A numerical investigation of slope stability influenced by the combined effects of reservoir water level fluctuations and precipitation: A case study of the Bianjiazhai landslide in China

Slope failure near a reservoir area is mainly influenced by rainfall and reservoir water fluctuation. This study provides insights into the deformation and failure process of the Bianjiazhai landslide near the Suofengying reservoir located at the Wu River in Guizhou province, China. Firstly, stability analyses were carried out to assess the overall strength of the slope and identify the most vulnerable section of the site. Secondly, transient hydromechanical analyses were performed to analyze the effects of rainfall and the reservoir water level fluctuations on the selected slope. The hydromechanical analysis is divided into three different scenarios to study combined as well as the individual effects of rainfall and reservoir water level fluctuation on slide formation. The results indicate that the sudden reservoir water level fluctuations are critical for the stability of the slope. Strength reduction analyses confirm that the deformation behavior of the slope is dominated by shear slip phenomena and identify relevant shear zones. The numerical results from both hydromechanical and stability analysis indicate that the stability of the slope is greatly reduced during large and sudden drawdown. The results from this study will be useful for preventing landslide disasters and for guiding reservoir operation in a similar context. © 2021 Elsevier B.V.