Failure modes and a calculation method for a stability analysis on a layered slope with a focus on interlayer sliding

Abstract

Geotechnical body is often heterogeneous in both of the natural and artificial slopes, and the layered slope is a special case. The previous studies have discussed in depth the stability of a layered slope. However, the research on the local stability of a layered slope with a focus on interlayer sliding is still insufficient. Due to the difference on the strength of soils in the adjacent upper and lower layers, it is possible for the local stability with the sliding along the interface between the adjacent two layers. Meanwhile, compared with the global stability of a layered slope, a complex sliding model should be adopted to simulate the local stability for the reason of its failure pattern affected by the forces on the interface of the two adjacent layers. Thus, this work establishes two failure modes of a layered slope, i.e., the global stability and the local stability with a focus on interlayer sliding. Then, on basic of the proposed limit equilibrium (LE) stress method, the formulas for calculating the slope factor of safety (FOS) under the two failure modes are derived. After comparison and analysis on some slope examples, the feasibility of the proposed method is verified. Furthermore, the parameter analysis is performed on a layered slope composed of soils with two layers, where the shear strength of soil in the upper layer is weaker than that in the lower layer. Thereby, the stability charts of a layered slope under different conditions are drawn. Moreover, the scopes for the global and local stability of a layered slope are respectively identified in these charts.