Introduction

The position of the critical slip surface depends on the parameters used to describe the shear strength of the modeled domain. For example, the critical slip surface may vary when using effective stress strength parameters instead of equivalent total stress parameters. This phenomenon is not always obvious in slope stability analyses and, consequently, can be the source of some consternation when interpreting the computed factors of safety. This document seeks to address this issue and give recommendations on selecting shear strength parameters when the position of the critical slip surface is of importance in a stability analysis.