The Effect on Stability of Slope under Drawdown Conditions

Abstract

The program of PLAXIS was adopted to analyze the slope stability. The ideal elastic-plastic model and the yield criterion of Mohr-Coulomb theory were simulated numerically for the realistic project. The drainage condition and undrained condition of the soil body were compared. The calculation shows that the safety factor declines with the drawdown of the water level under the drainage condition. However, the safety factor would rise after the water level drops by 20 meters, which is caused by the vertical acting force of the pore pressure, and its influence on the safety factor of the slope is more obvious under the undrained condition. The safety factor with the excess pore pressure is 10% lower than that without regard to the pressure. As a result, the accumulation and dissipation of the excess pore pressure should be taken into consideration in the practice. What’s more, the safety factor should be checked according to the “least favorable water level”. The program of PLAXIS can simulate the effect of seepage on the slope stability when the water level drawdown in calculation.