New Instability Criterion for Stability Analysis of Homogeneous Slopes

A new instability criterion based on the strength reduction method (SRM) is proposed, where the slope is in the limit equilibrium state when the critical slope contour determined by the slip-line field theory and the slope intersect at the toe of the slope. The proposed method was validated using a published case. Compared with the traditional instability criterion, the SRM with the displacement finite-element method, the SRM based on the Davis algorithm, and finite-element limit analysis, Spencer's method, the proposed method is more suitable for slope stability analysis. The safety factor was calculated separately from the critical slip surface. As such, the critical slip surface is determined without involving an optimization or iteration. The proposed method recognizes the objective quantification of the instability criterion.