Unified Overload Method of Slope Stability Analysis Based on Potential Sliding Direction

The overload method is difficult to be promoted in slope stability analysis for its disunity of loading forms and directions. Based on the traditional overload method and the Strength Reduction Method (SRM) in which the limit equilibrium state of the slope was reached by reducing sliding resisting force without changing the sliding force, a new way to reach the limit equilibrium state of the slope was developed by increasing sliding force without changing resisting force. Referring the loading forms in Gravity Increase Method (GIM) and sliding direction determination in Vector Sum Method (VSM), the theoretical relationship was built between overload coefficient and safety factor of Vector Sum Method (VSM) and the unified overload method based on overall potential sliding direction was proposed. The loading forms and directions were unified by this method, respectively. Sliding surface could be determined while solving the safety factor and the developing direction of overload method in slope stability analysis application was indicated. Three representative slopes with fixed sliding surfaces and two slopes with unknown sliding surfaces were taken as examples to compare results from Limit Equilibrium Method (LEM), Strength Reduction Method (SRM), Vector Sum Method (VSM), Gravity Increase Method (GIM) and overloading method along the horizontal direction with each other. The safety factor resulted from the method proposed in this paper was close to the one from Vector Sum Method (VSM) and the location of sliding surface was close to the one from Strength Reduction Method (SRM). Thus the reliability of the method was testified.