LAUSR

Abstract The presence of cracks in soil slopes is of major concern to researchers and engineers, as this phenomenon is typically considered to be an early indication of instability and potential landslides. In this study, the kinematical approach of limit analysis was applied to evaluate the three-dimensional (3D) stability of soil slopes with pre-existing cracks and the reinforcement effects of piles. A vertical crack was accommodated in the classical 3D rotational failure mechanism by introducing a velocity discontinuity surface. Formulas for the external work rates and internal energy dissipation rates of the failure mechanism were derived within the framework of limit analysis. An optimization program was developed in combination with the strength reduction method to search for the most critical failure mechanism and the corresponding upper-bound factor of safety. A new parameter, the maximum crack depth coefficient, was introduced for evaluating the sensitivity of slopes to the presence of cracks. The numerical results indicated that slopes with large inclination angles are extremely sensitive to natural cracks, whereas gentle slopes are less likely to be affected. It was also found that stabilizing piles could effectively restrict the depth of the crack opening and thus, improve the stability of fissured slopes; the reinforcement effect was extremely dependent on the installation location and the density of the pile group.