Nonlinear Analysis of Pseudo-Dynamic Active Earth Pressure Considering a Multi-segment Rotational Failure Mechanism

This paper presents a novel method for assessing the seismic active thrust in cohesive soils governed by the nonlinear Mohr–Coulomb strength criterion. To characterize the nonlinearity of shear strength envelope, the available studies either simplify it as a linear relationship or substitute a single tangent line for that. However, considering the distribution characteristics of soil stress and the mapping relationships between the strength envelope and soil failure surface, these approximations are a bit rough. To fill the research gap, a piecewise linear method (PLM) is herein introduced, which correspondingly generates a multi-segment rotational failure mechanism according to the associated flow rule. The mechanism can be determined by 2n + 1 (n = 10 in this work) independent angle variables and a time variable. Furthermore, a modified pseudo-dynamic approach is properly implemented to quantify seismic load. This approach involves using a layer-wise summation method to address the earthquake-induced inertial power. The normalized expression of active thrust associated with various parameters can be derived from the work rate balance equation. Then, a classic genetic algorithm (GA) is applied to optimize this multi-variable function. In terms of accuracy, the active thrust obtained by the proposed method (n = 10) is superior to that obtained by the generalized tangential technique (GTT, n = 1), and the improvement becomes more apparent as the nonlinear parameter increases.