Influence of Hoek-Brown linearization and input cross-correlation in slope Probability of Failure Calculation

Author(s): 
Cristóbal Valderrama, Felipe Sanz and Esteban Hormazábal
Date: 
Monday, November 19, 2018
First presented: 
3rd South American Symposium on Rock Excavations 2018
Type: 
Published paper
Category: 
Geotechnical

When Hoek-Brown failure-criterion (H-B) is selected, their parameters are determined as the ones that better fit data; therefore, depends on the method of fitting, the experimental error and statistical sufficiency of data. If these uncertainties are considered, H-B parameters are random variables. On the other hand, in slope stability analyses, is common to linearize the H-B criterion to estimate equivalent friction angle, фe, and cohesion, ce, which generate a non-lineal relation between фe and ce. In this paper, we examine the effect of this linearization in probabilistic analyses that use a Mohr-Coulomb criterion when the input data are random H-B parameters. We study the uncertainty propagation from H-B parameters to фe and ce. Additionally, because linearization cross-correlate фe and ce, we analyze the effect of the correlation ρфc in Factor of Safety (FS) and Probability of Failure (PoF) results, finally because also H-B parameters can be correlated we examine the effects on FS and PoF.

 

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