Limit Equilibrium Analysis of Slope Stability with Coupling Nonlinear Strength Criterion and Double-Strength Reduction Technique

Currently, the strength parameters are reduced by a uniform coefficient for the traditional strength-reduction technique in the slope stability analysis. However, observations proved that the contributions of the strength parameters on slope stability are different from each other when the slope reaches the limit equilibrium (LE) state, which means that the strength parameters should be reduced with their own reduction coefficient. Thus, based on the assumptions of stresses on slip surfaces and the overall mechanical equilibrium conditions of the slope sliding body, this work establishes the LE solution for slope stability under the double-strength reduction (DSR) technique. In the LE stress-based analysis, the loop iteration strategy is given to solve the LE stability of slope with the nonlinear strength criterion. Moreover, a new method (i.e., the square root method) is proposed to calculate the slope comprehensive factor of safety (FOS) for evaluating the slope stability with application of the DSR technique. Thus, by comparing and analyzing some slope examples, the accuracy of the present method is verified. Furthermore, from the obtained stability charts of slope under the DSR technique, the study shows that if the characteristic stability number is less than 0.04 for clay soil, then the internal friction angle would have a larger contribution to the slope stability than cohesion; whereas if the characteristic stability number is more than 1.00, then the larger contributor on the slope stability would be the cohesion.