A new perspective on determination of the critical slip surface of three-dimensional slopes

In the traditional slope stability analysis, the shape and location of critical slip surface (CSS) are identified by an objective function with the minimum safety factor (SF). However, the method cannot identify the true CSS when the minimum SFs of different critical slip surfaces are equal or extremely close. In order to solve the issue, the idea of slip surface with the maximum sliding direction (SD) as the CSS is proposed in this paper. The shape of CSS is regarded as a rotational ellipsoid with 6 parameters, and the genetic algorithm (GA) is adopted to search for the location of CSS. The three-dimensional (3D) slope stability analysis is performed based on the minimum potential energy principle, which provides an analytical formulation of SD as well as SF without iteration. Two benchmark slopes and a practical engineering case are employed to verify the rationality of the proposed method. The parametric analysis reveals that the larger SD the smaller SF. The developed method is a useful technique support for determining the CSS and the shape of 3D slope.