Random Field Modeling of Foundation Failure Modes

Two different models for reliability analyses of foundation failure problems are presented, one where only average soil-strength properties are modeled, and one where the soil strength is represented more accurately as a random field. Two example cases are presented, namely static pull-out of a vertical pile and horizontal sliding of a gravity-base structure, both installed in clay. Uncertainties in environmental loading as well as in soil-strength properties are modeled. The spatial fluctuation structure of the soil strength is estimated by means of a kriging technique. Reliability calculations for the two example foundations are performed by first-order reliability methods. For each example foundation the results of the two different types of reliability analyses are compared, and the effect of representing the soil strength as a random field is assessed.