Three-Dimensional Stability Analysis of Bank Slopes with Reservoir Drawdown Based on Rigorous Limit Equilibrium Method

The fluctuation of reservoir water levels has significant impact on bank slope stability near a reservoir. Therefore, it is necessary to analyze the stability of bank slopes with reservoir drawdown. In this paper, a novel method combining the seepage force with rigorous limit equilibrium method is proposed to analyze the stability of bank slopes near the reservoir. First, the calculation method of the phreatic surface and the seepage force is developed. Then, six equilibrium equations are established based on the equilibrium conditions of three forces along the coordinate axis and the equilibrium conditions of three moments around the coordinate axes. Finally, a trust-region-reflective iterative algorithm is used to determine the safety factor of bank slopes from these six equations. Moreover, the effects of drawdown speed, the height of the drawdown, permeability coefficient, and the aquifer thickness on bank slope stability are investigated using the proposed method. Two engineering cases of Ataden I landslide and Guanyinping landslide are used to verify the correctness and practicability of the proposed method.