The long-term stability analysis of 3D creeping slopes using the displacement-based rigorous limit equilibrium method

•A novel method is presented to analyze long-term stability of 3D creeping slopes.•The displacements of slopes are taken into consideration.•The visco-elastoplastic creep model is introduced into the proposed method.•The strength reduction technique is introduced into the proposed method.

The conventional limit equilibrium method is hardly applied to investigate the stability and the displacement of creeping slopes. In this paper, a novel displacement-based rigorous limit equilibrium method is proposed to analyze the stability and the displacement of three-dimensional (3D) creeping slopes. The relationship between the shear displacements of the slopes and the creep time is obtained based on the visco-elastoplastic creep model. According to the displacement compatibility among the columns, the shear displacements of all columns can be described by the vertical displacements at the key point. Combining the six equilibrium conditions of the discretized columns with the visco-elastoplastic creep model, the vertical displacement at the key point can be determined. With increase of creep time, the vertical displacement at the key point converges to a constant value. By introducing the concept of strength reduction technique into the displacement-based rigorous limit equilibrium method, the relationship between the reduction factor (RF) and the long-term displacement at the key point can be obtained. Then, the long-term factor of safety of 3D creeping slope is equal to the value of the reduction factor at the point of sharp increment of displacement. Two case studies are given to verify the robustness and precision of the proposed method.