Abstract
This paper studies the probability distribution for the mobilised shear strength of a spatially variable soil mass that is subjected to a uniform stress state. Based on the mechanisms identified in two previous studies conducted by the authors, this study further proposes a probability distribution model for the mobilised shear strength that is based on the extreme value of normal random variables. It is concluded that the probability distribution of the mobilised shear strength of a spatially variable soil mass is affected by the line averaging effect along the potential slip plane and the number of independent potential slip planes. These two factors depend on the stress state and the orientation of the potential slip planes. With this model, the mobilised shear strength of a spatially variable soil mass can be simulated without the need of conducting random-field finite-element analyses. In addition, the strength characteristic value that is the 5% quantile in the Eurocodes can be easily derived from this model.