Abstract: The colluvial slopes are widely distributed in southwestern China, and the reservoir pooling water level variation and earthquakes are the main factors inducing the stability issues in colluvial slopes. Studying the stability of colluvial slopes under the effects of earthquakes and reservoir pooling water level fluctuations is of the great engineering significance. The stability evaluation of a typical bank slope of the Jinji Dadan River Bridge in Yunnan Province in presented in this paper. Based on the coupling theory of the stress and seepage, the stability of a colluvial slope under 10 different conditions of the reservoir pooling water level variations is evaluated in the paper. Based on the theory of equivalent linear analysis, the dynamic response of the water reservoir slopes under different seismic loads are studied by using the finite element and limit equilibrium M-P methods. The dynamic stability evaluation of slopes is performed from two aspects: the factor of safety and the permanent displacement, respectively. The results indicate that the factor of safety of the slope is greater than the critical value during the change of reservoir pooling water level, and the possibility of the slope instability is small; When subjected to a VIII degree earthquake, the dynamic factor of safety and the permanent displacement of the slope indicate a very high risk of instability. The investigation results can provide a technical support for the safety assessment of slopes similar to the bank deposits under the variations in reservoir pooling water level and seismic action.

Key words: Colluvial Slope, Reservoir Pooling Water Level Variation, Earthquake, Stability, Factor of Safety, Permanent Displacement