Abstract: Environmental factors such as fluctuation in reservoir pool level and sudden heavy precipitations are important factors that cause the bank slope instability. Most of the landslides that instable, continue to deform and marginally stable are mostly caused by the rainfall and changes in reservoir pool levels. The change of seepage field induces landslide deformation and instability to induce in geological hazards. This paper studies the stability variation of the Fujiapingzi landslide on the Jinsha River reservoir bank during one cycle of reservoir water dispatching. The finite element analysis software GeoStudio was used to evaluate the stability of the bank slope by environmental factors such as changes in the reservoir pool level, precipitation and their combined effects. The results show that, within a reservoir pool level dispatching cycle, the most instable moment of the Fujiapingzi landslide was when the reservoir pool level drops to Elevation 540 m (in May), and the most instable location was at the front edge of the landslide, and the overall landslide was potentially instable; The landslide safety factor changed during the pool level scheduling period is basically consistent with the changing trend of the reservoir pool level. When the reservoir pool level remained unchanged, the rise of the groundwater level would reduce the rock and soil mechanical strength parameters, which would affect the stability of the slope, and the safety factor of the bank slope would decrease; when the reservoir water level raised, the seepage force generated by the infiltration and the hydrostatic pressure on the opposite bank slope were greater than the buoyant drag force generated after the front edge of the sliding body was submerged, and the safety factor was improved. As the reservoir water level decreased, the stability of the slide body decreased, indicating that the seepage force in the slope and the reservoir water pressure on the front edge of the landslide played a leading role.

Key words: Reservoir Bank slope, Stability Analysis, Limit Equilibrium, Reservoir Pool Level Change, Precipitation