Simplified stability analysis of strain-softening slopes under drawdown conditions

The progressive failure of slopes is often induced by drawdown and strain-softening of the soil. Thus, the stability level of a strain-softening slope under drawdown conditions should be evaluated while considering progressive failure. A simplified method was developed to analyze the stability of a strain-softening slope based on a new algorithm for determining the subsidiary shear deformation under drawdown conditions. The parameters of the method could be easily determined. The predictions of the failure behavior of the slope that were obtained using the proposed method were close to the observations of centrifuge model tests under drawdown conditions. Thus, the method was confirmed to be effective in analyzing the stability evolution of the strain-softening slopes induced by the drawdown of water level. This proposed method was used to evaluate the stability of a real-world slope under drawdown conditions. The results showed that there is a significant evolution in the safety factor of the slope as the water level decreases. The safety factor of a slope is overestimated if the progressive failure behavior is not considered. The strain-softening behavior and initial water level have a significant effect on the safety factor and critical slip surface of the slope.