Calibratable Rock Mass Shear Strength for Open Pit Slopes
DOI:
https://doi.org/10.17159/Abstract
Open pit slope stability analyses for large scale instabilities are often carried out using Limit Equilibrium, Finite Element or Finite Difference computer programs. All of these require empirical estimates of rock mass shear strength when calibrated values are not available, which, is a common occurrence. A common method of estimating rock mass shear strength is the Hoek-Brown failure criteria, however, this method often over or underestimates rock mass shear strength when used in Limit Equilibrium or Elastic Linearly Plastic slope stability analyses, resulting in published alternative estimates for the coefficients of the Hoek-Brown failure criteria.
This paper investigates the differences between Limit Equilibrium and Elastic Linearly Plastic slope stability analysis based on the Hoek-Brown failure criteria. The investigation consisted of a comparison of 3840 RS2 Finite Element analysis models completed with strain softening, and 216 Slide2 Limit Equilibrium models. The models were used to evaluate a methodology to determine equivalent Limit Equilibrium and Elastic Linearly Plastic shear strength parameters that provide the same stable slope angles and instability back break distances as the more representative Strain Softening stress analysis methods This paper presents the methodology, and compiles the results into design charts and equations for equivalent Limit Equilibrium Mohr-Coulomb shear strength parameters, that simplifies calibration against actual case studies. The results compare well with older empirical shear strength estimates, however, a detailed calibration of the results against case studies will need to be carried out.
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Copyright (c) 2026 Julian Venter, Callen Banff, E.C.F. Hamman
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