Failure Mechanism and Factor of Safety for Spatially Variable Undrained Soil Slope

Abstract

This paper aims to investigate the differences in factor of safety (FS) and failure mechanism (FM) for spatially variable undrained soil slope between using finite element method (FEM) , finite difference method (FDM), and limit equilibrium method (LEM). The undrained shear strength of cohesive soil slope is modeled by a one-dimensional random field in the vertical direction. The FS and FM for a specific realization of random field are determined by SRT embedded in FEM- and FDM-based software (e.g., Phase2 6.0 and FLAC) and LEM, respectively. The comparative study has demonstrated that the bishop method (with circular failure surface) exhibits performance as fairly good as that of SRT both in FS and FM for the undrained slope cases where no preferable controlling surfaces such as hydraulic tension crack and inclined weak seams dominate the failure mechanism. It is, however, worthwhile to point out that unconservative FM is provided by the Bishop method from the aspect of failure consequence (i.e., the failure consequence indicated by the FM from the Bishop method is smaller than that from SRT). The rigorous LEM (e.g., M-P and Spencer method with noncircular failure surface) is not recommended in the stability analysis of spatially variable soil slopes before the local minima and failure to converge issues are fully addressed. The SRT in combination with FEM and/or FDM provides a rigorous and powerful tool and is highly preferable for slope reliability of spatially variable undrained slope.

Cohesive slope failure analysis using methods combining smoothed particle hydrodynamics and response surface function

“…With regard to failure consequence, its quantification seems a little complicated considering the site-specific structures, the people and the infrastructure that may be endangered by a landslide. As a simplified solution, the area of a sliding mass during a landslide is a straightforward index to represent the failure consequence, and this index has been adopted in landslide risk analysis by many researchers (Huang et al , 2013; Zhu et al , 2015; Li et al , 2016; Zhang and Huang, 2016; Li and Chu, 2016, 2019; Chu et al , 2019). In previous research, the area of sliding mass (denoted by A ) corresponding to the slip surface with a minimum factor of safety (FS min ) was used to quantify the failure consequence of the landslide by using either limit equilibrium method (LEM) (Li and Chu 2016,2019) or strength reduction method (SRM) with conventional finite element method (Li et al , 2016) or finite difference method (Zhang and Huang, 2016), or by using limit analysis (LA) (Huang et al , 2013).…”

Time History Method of Three-Dimensional Dynamic Stability Analysis for High Earth-Rockfill Dam and Its Application

“…Early researchers calculated the safety factor based on the stress distribution obtained by the linear elastic finite element method, and the results were close to the limit equilibrium method. Li [30] studied the differences between the safety coefficient and the failure mechanism of spatially variable undrained soil slope using the finite element method, finite difference method and limit equilibrium method.…”

Modal Analysis of Beam Structures with Random Field Models at Multiple Scales

“…e random field theory is an effective method for simulating such spatially varying and autocorrelated material properties [46][47][48][49][50]. For simplicity, this work focuses on stationary random fields, where (1) the distribution, as well as the corresponding statistics, of each variable remains constant everywhere and (2) the correlation between the variables at different locations depends only on the separation distance [51,52].…”