Slope stability analysis: Barodesy vs linear elastic – perfectly plastic models

Franz Tschuchnigg,Gertraud Medicus,Barbara Schneider-Muntau,A Tarantino,E Ibraim

doi:10.1051/e3sconf/20199216014

Franz Tschuchnigg, Gertraud Medicus + Show 3 more

Open Access

https://doi.org/10.1051/e3sconf/20199216014

Copy DOI

Abstract

The results of slope stability analysis are not unique. Different factors of safety are obtained investigating the same slope. The differences result from different constitutive models including different failure surfaces. In this contribution, different strength reduction techniques for two different constitutive models (linear elastic - perfectly plastic model using a Mohr-Coulomb failure criterion and barodesy) have been investigated on slope stability calculations for two different slope inclinations. The parameters for Mohr – Coulomb are calibrated on peak states of element tests simulated with barodesy for different void ratios. For both slopes the predictions of the factors of safety are higher with barodesy than with Mohr-Coulomb. The difference is to some extend explained by the different shapes of failure surfaces and thus different values for peak strength under plane strain conditions. The plane strain predictions of Mohr-Coulomb are conservative compared to barodesy, where the failure surface coincides with Matsuoka-Nakai.

Highlights

Strength reduction techniques are a widely used method to calculate factors of safety in Finite Element calculations
Constitutive models including the Mohr - Coulomb failure criterion are used for strength reduction finite element analysis (SRFEA)
Plane strain conditions are more relevant than axisymmetric conditions

Summary

Introduction

Strength reduction techniques are a widely used method to calculate factors of safety in Finite Element calculations. In this method, the strength parameters are reduced gradually until failure occurs. Constitutive models including the Mohr - Coulomb failure criterion are used for strength reduction finite element analysis (SRFEA). The Mohr - Coulomb model (linear elastic perfectly plastic) does not take into account effects of changes in density and effects like softening cannot be modelled. Results of slope stability analyses of conventional elasto – plastic models using a MC failure criterion are compared with results of strength reduction applied to barodesy. Finite element limit analyses (FELA) are carried out. Since FELA provides rigorous solutions these results are used as reference solutions for comparisons

Barodesy

Calibration

Calibration Results

Applications in Strength Reduction Calculations

Results of the Strength Reduction Analyses

Conclusion