Comparative study of stability analysis methods for slopes with weak soil layers

Lei Huang , Leilei Liu

Abstract

This paper revisits a classical topic in the geotechnical profession, i.e., how to select an appropriate method for slope stability analysis. This study focuses on slopes with weak soil layers, and the methods investigated are the typical approaches based on the frameworks of limit equilibrium method (LEM), finite element method (FEM) and limit analysis (LA). This study includes the LEMs, finite element stress method (FESM), strength reduction method (SRM) and discontinuity layout optimization (DLO). It is found that when dealing with slopes with weak soil layers using LEM, there are higher requirements for the factor of safety (FS) iteration algorithm. The difficulty in convergence of FS during iterative solution may occur due to the assumption regarding the inter-slice force, which may cause overestimated FS with relative error exceeding 45% for a slope with a weak foundation layer. Meanwhile, the inherent transition of failure mechanisms of slopes with weak layers increases the difficulty in determining the critical slip surface by LEMs. The non-convergence issue is avoided in FESM, but its FS results are sensitive to the model domain and element size for a slope with a thin soft band (FS results ranging from 0.439 to 1.238 under different element sizes and model domains), exhibiting unsatisfactory performance under complex conditions. In general, DLO has better performance in analyzing the stability of slopes with weak soil layers, especially in capturing the failure mechanism.

Key Words

discontinuity layout optimization (DLO); failure mechanism; finite element method (FEM); limit equilibrium method (LEM); slope stability analysis

Address

Lei Huang — College of Architecture and Civil Engineering, Sanming University, Sanming 365004, China; Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong, China; Key Laboratory of Intelligent Construction and Monitoring of Engineering Structures in Fujian Province College, China
Leilei Liu — Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring, Ministry of Education, School of Geosciences and Info-Physics, Central South University, Changsha 410083, China

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