RELIABILITY-BASED CHARACTERISTIC VALUES: A STOCHASTIC APPROACH TO EUROCODE 7

This paper presents a stochastic approach to quantifying reliability based, characteristic values, satisfying the requirements of Eurocode 7 (env 1997-1(1994) Eurocode 7: Geotechnical design - Part 1 General rules). The method for determining these values is demonstrated for a simple slope stability problem. The results show that reliability is a more meaningful measure of stability than conventional factors of safety for which there is no information regarding probability of failure. They also show that spatial variability is an important factor in stability assessments and that proper account should be taken of its anisotropic nature. However, an accurate knowledge of the degree of anisotropy (of the heterogeneity) may not always be needed. Recommendations are made for future research in this subject area. The stochastic procedure may be split into three stages, the pre-analysis stage, involving the preparation of statistical and material data; the analysis stage, comprising repeated realisation of the same problem as part of a Monte Carlo simulation; and the post-analysis stage, in which the results of the realisations are themselves expressed in probabilistic form. (A)