Torque sum method for slope stability analysis

A new method for analyzing slope stability, the torque sum method (TSM), is proposed. The TSM is on the basis of the vector sum method (VSM), considering the displacement mode of the landslide mass as a rigid body and supplementing the displacement tendency of rotating around a certain point. The TSM assumes, for a definite landslide mass and sliding surface, that the mass rotates around a certain point, and by calculating the sum of the rotating torques and the anti-rotating torques of the slide body, the factor of safety when the landslide mass rotates around a certain point is obtained. In this work, the definition of the factor of safety for the TSM is given, and the formula for solving the factor of safety as well as the corresponding calculation steps are derived based on the sliding surface stress of the slice method model. Two examples of ACADS are solved by the TSM, and the results of circular and non-circular sliding surfaces are compared with those of other representative methods. The results show that a smaller factor of safety is obtained by the TSM than by the traditional methods, which is worthy of attention in slope stability analysis. The proposed TSM is a supplement to the VSM which only considers the linear translational displacement mode of sliding body, and also provides a new way for slope stability analysis, especially the possible rotational displacement mode of landslide mass.