Discretization-Based Kinematic Approach for Three-Dimensional Stability Analysis of Slurry Trenches in Cohesive–Frictional Soils

Abstract

Although trench failures observed in the field clearly show three-dimensional (3D) characteristics, the stability analyses of slurry-supported trenches are typically carried out under plane-strain assumptions. The factor of safety on trench stability produced by two-dimensional studies is also regarded as conservative as the favoring 3D end effects are not considered. To address this issue, a 3D rigid rotational mechanism formulated by a spatial discretization scheme is proposed for the stability analysis of slurry trenches in cohesive–frictional soils. The proposed method agrees well with the upper-bound solutions and corresponding optimal failure profiles of conventional rigid rotational mechanism (horn mechanism) of long trenches. Further improvement is achieved for short trenches as the discretization technique allows the mechanism to be generated with any given boundary conditions without assumption of standard geometry. Discussions on the influence of slurry parameters and soil strength parameters on trench stability are presented with results in the form of stability charts for convenience of application in practice.