Reliability analysis of raft foundation on uniformly random soils

Abstract

The mode of failure associated with settlement is invariably observed to be critical with regard to the performance of raft foundation. The inherent randomness in the associated parameters necessitates a probability-based assessment and design of raft. This paper presents settlement analysis of a raft foundation accounting for randomness in the design parameters in the framework of probability theory. Uncertainties involved in the elastic modulus of the raft, modulus of subgrade reaction of the soil and loading on the raft areaccounted for in the analytical soil-structure interaction model.The point estimate method (PEM), the first order second moment method (FOSM) and the first order reliability method (FORM) are used to evaluate the probability of failure and reliability index associated with the settlement of the raft foundation. Parametric sensitivity analysis is also carried out to identify the important design variables that affect the performance of the raft foundation with respect to settlement. The information obtained from the analysis can be employed in reliability-based design of rafts.