Investigation of deformation failure mechanism and stability of the guobu reservoir slope at laxiwa hydropower station

The stability of a slope at a hydropower station is closely related to variations in water storage levels. At China's Yellow River Laxiwa Hydropower Station, although operations have been at normal water level since 2015, slope deformation intensified and local instability occurred during the impoundment process. Therefore, it is important to research the mechanism of landslides, predict possible landslide phenomena and introduce treatment measures. The Guobu slope, situated on the right bank of the Laxiwa Hydropower Station, was chosen as the research object in this paper. The three-dimensional distinct element method (DEM) was used to investigate and calculate the slope deformation and stability under different water levels. The numerical results accurately simulate the in-situ toppling deformation of the Guobu slope instability and demonstrate that impoundment and geological structures are the dominant factors contributing to the slope's significant deformation. Based on slope stability analysis, slope-cutting measures were proposed, and the modified strength reduction method was applied to the factor of safety (FOS) calculation. We use 3DEC to analyze the control factors of deformation and failure of Guobu slope instability accurately. Our findings contribute significantly to the understanding of toppling mechanisms in steep slopes, revealing how complex geological structure and reservoir level fluctuation interact to trigger instability.