ABSTRACT
Traditionally, safety factors in geotechnical engineering are defined by the largest possible reduction in shear strength at incipient failure. In numerical, elasto-plastic finite element calculations this definition is straight-forward to implement for the standard Mohr-Coulomb model. However, for models defined by non-linear Mohr envelopes it is not straight-forward to implement the standard definition of the safety factor. The problem being that material models in numerical codes are usually defined in cartesian stress space rather and by Mohr envelopes. This paper presents a consistent implementation of slope safety factors for elasto-plastic simulations using non-linear Mohr envelopes. The presented method renders comparisons of safety factors across different material models meaningful, and also allows for having different non-linear material models in the same calculation domain when performing shear strength reductions for obtaining the safety factor.
