Failure Mechanism of Two-Layered Slopes Subjected to the Surcharge Load

Abstract

For some two-layered slopes subjected to the surcharge load, the soil mass undergoes rotational or translational movement. Thus, the conventional failure mechanism of homogeneous slopes is no longer applicable. To overcome the difficulty in stability assessment of two-layered slopes, a rotational-translational failure mechanism is proposed, and it is composed of rigid blocks rotating around the center point or sliding along the layered boundary. Meanwhile, two rotational failure mechanisms (face and base failures) are modified to evaluate the stability of two-layered slopes with upper bound limit analysis. Case studies and stability charts are carried out on two-layered slopes with various surcharge loads, slope geometries, and soil strengths. The results are useful to address advantages and application differences of the three failure mechanisms in engineering practice. In addition, the comparison with the Spencer method indicates that the upper bound solution of the rotational or rotational-translational mechanism in different conditions is more rigorous because of the lower factor of safety and the more reasonable slip surface.