Analysis of stability of dam slope during rapid drawdown of reservoir water level

The stability of dam slope during rapid drawdown of reservoir water level was computed using limit equilibrium method and limit equilibrium method based on finite element analysis according to unsaturated soil shear strength theory in combination with a specific reservoir. In this computing process, the dissipating process of pore-water pressure was simulated using unsaturated-unsteady seepage theory and the impact of matric suction on shear strength of soil body was taken into consideration, each step of seepage corresponding to a stable situation of the dam. Finally, the comparison between both of stability analysis methods was made. It is found that the rapid drawdown of reservoir water level easily results in the dam slope slipping; the stability of dam slope is enhanced with the dissipating process of water pressure in the dam body; and the matric suction increases the shear strength in this dissipating process.