A Novel Limit-Equilibrium Method Based on Increments of Interslice Forces for Stability Analysis of Slopes with Weak Interlayers

The existence of weak interlayers (WIs) in slopes results in slope failure with multiple possibilities. The most likely failure modes include sliding along a curved slip surface, linear slip surface, and composited slip surface. As such, WIs are highly sensitive to slope stability results, and dense slice division is necessary for limit-equilibrium (LE) stability analysis of the slopes with WIs. However, considering the stability of a complex slope dependent on the dense slice division, the traditional rigorous LE methods have the problem of nonconvergence calculation for possible interference from unreasonable interslice moment results. Thus, this study established a novel LE method based on increments in interslice forces (ISFs). The proposed method had good convergence with the introduction of the overall moment equilibrium condition and rigorously satisfied the end boundary conditions of both normal and shear ISFs. Thereafter, the reliability of the proposed method was verified by comparing and analyzing several examples. Furthermore, stability charts for slopes with WIs were realized based on a large amount of statistical data on typical occurrence and strength parameters to provide guidance for slope design.