Kinematic Stability of a Two-Stage Slope in Layered Soils

Abstract

This study presents a closed-form solution for kinematic stability of a two-stage slope with a strip footing placed near the slope crest of the layered soil strata. According to the upper-bound theorem of plasticity theory, the normalized ultimate bearing capacity and yield seismic coefficient that the slope could withstand without failure under the limit state are derived on the basis of the pseudostatic approach. In addition, under specific parameters, the least upper-bound solutions can be calculated with the use of optimization. The stability factors were compared with those in existing literature under static, seismic, and undrained conditions to validate the proposed approach and the analytical solutions. A thorough parametric study involving parameters, such as soil cohesion and self-weight, nonhomogeneous coefficients, and external conditions (including the magnitude and position of strip footing and seismic effect), was carried out in this study. The findings obtained, considering a log-spiral failure mechanism under drained conditions and a circular mechanism for undrained conditions, could provide useful reference for the preliminary design of a two-stage layered slope.