Probabilistic Approach to Design OF Embankments

Abstract

Safety factors of embankments are analyzed in relation to the variabilities and the uncertainties of soil properties. It is concluded that the unconfined compression strength of a saturated homogeneous clay layer and the strength parameters c u and tan ϕ u of an unsaturated homogeneous silty soil layer follow the theoretical normal distributions. Such physical properties as moisture content and moist density of those soil layers and moist density of an embankment just after construction are also shown to be taken as the normal random variables. A new design factor is defined and the relation between the design factor and the probability of sliding fuilure of an embankment is formulated under consideration of the randomness of the soil properties. Numerical and practical examples show that the embankment with an ordinary value of the design factor ( F s *= 1 . 1—1.5) has an unexpected high value of the probability of sliding failure as 15%~20%.