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Probabilistic Stability Analysis of Slopes in Highly Heterogeneous Rock Masses
Hossein Rafiei Renania,*, C. Derek Martina, Pedro Varonab and Loren Lorigc
a Department of Civil & Environmental Engineering, University of Alberta, Edmonton, Canada
b GeoControl Ltd, Santiago, Chile
c Itasca Consulting Group Inc, Santiago, Chile
*Corresponding author contact information: rafi firstname.lastname@example.org (H. Rafiei Renani)
This study aims at developing a robust methodology to quantify and incorporate variability into stability analysis of slope in highly heterogeneous rock masses. A series of standard or index tests on small samples along with numerical tests on large samples can be used to estimate geomechanical variability at the slope scale. Statistical distribution of rock mass strength can be introduced into slope stability analysis to determine the distribution of Factor of Safety (FOS) and Probability of Failure (POF). Two example slopes are analyzed using Limit Equilibrium Analysis (LEA) and Strength Reduction Method (SRM) implemented in a finite difference code. Both methods showed that increasing strength variability leads to reduction of mean FOS and increase of POF for the analyzed slopes with deterministic FOS>1. In both examples, mean FOS calculated from SRM is slightly lower than that obtained from LEA. Compared to LEA, SRM also gave a lower POF for low to intermediate levels of strength variability and higher values at very high levels of strength variability. Such differences were discussed in terms of different spatial variability in the models. The relationship between strength parameters of deterministic and probabilistic models giving similar FOS was explored.
(a) Distribution of cohesion in the slope with COV=0.5, (b) probability distribution of cohesion values in the elements.