This paper aims to develop an effective method for quantifying the risk of slope failure and identifying the sources of failure risk by combining the limit equilibrium method (LEM) and the final slip surface (FSS) simultaneously having factor of safety (FS) = 1 and the maximum area of sliding mass.
First, the LEM is used to calculate the stability of slope. Then, the verified dual-criteria final slip surface approach is used to accurately identify the risk sources of slope failure considering the two-dimensional spatial variability of soil properties. Finally, a framework combining LEM, FSS method and Monte Carlo Simulation (MCS) is proposed to accurately calculate the risk of slope failure. The proposed methodology is illustrated using three typical cofferdam models.
The comparative results across three slope models show that the critical slip surface significantly underestimates the failure consequences of slope, leading to an underestimation of failure risk. However, the risk of slope failure calculated using the proposed FSS is significantly consistent with that derived from MFSS, both in terms of spatial distribution and magnitude, which indicates that the proposed FSS can accurately and reasonably assess the risk of slope failure for different types of slopes. It is worth noting that the accuracy of the proposed FSS depends on the difference threshold (d), below which the FS is regarded to be 1. When considering the drainage condition of slope, d suggests that the value should be within the range of 0.007–0.1, while its value is recommended to be between 0.03 and 0.05 for saturated clay slope.
A geotechnical engineer could use the proposed method to quickly and accurately calculate the risk of slope failure.
The proposed method provides a novel perspective for the reasonable quantification of risk of slope failure.
