Behavior of Piled Raft Foundation on Heterogeneous Clay Deposits Using Random Field Theory

In the case of problematic soils and tall buildings where the design requirements cannot be satisfied merely by a raft foundation, it is of common practice to improve the raft performance by adding a number of piles so that the ultimate load capacity and settlement behavior can be enhanced. In this study, the effect of spatial variability of soil parameters on the bearing capacity of piled raft foundation is investigated based on the random field theory using the finite difference software of FLAC3D. The coefficient of variation (COV) of the soil’s undrained shear strength, the ratio of standard deviation to the mean, was considered as a random variable. Moreover, the effect of variation of this parameter on the bearing capacity of piled raft foundation in undrained clayey soils was studied taking the Monte Carlo simulation approach and the normal statistical distribution. According to the results, taking into account the soil heterogeneity generally results in more contribution of the raft in bearing capacity than that of the homogenous soils obtained by experimental relationships, which implies the significance of carrying out stochastic analyses where the soil properties are intensively variant.