Abstract:Landslide is one of the most serious geological hazards in the Three Gorges reservoir regions. Since the reservoir was in operation in 2003,both reservoir water level descending and rainstorm infiltration have become major factors that affect the stability of landslide. According to the water level operation options considering the case of extreme rainfall in the Three Gorges reservoir region,transient seepage due to the descending of reservoir water level from 175 to 145 m and rainstorm infiltration is calculated using the finite element method. The transient pore water pressures are then used for limit equilibrium analyses of landslides considering the effects of suction on shear strength of unsaturated soils. The effects of different rainfall speed,various rainfall events on landslide stability are discussed. The results of stability analysis show that the stability of landslides by the drawdown of reservoir water level depends on permeability coefficient of landslides and the structure of landslide. The critical declining velocity of Hongshibao Landslide III is 1 m/d when the rainstorm intensity is 100 mm/d,which will provide scientific basis for the treatment of landslide in Three Gorges reservoir.