Effect of Preloading with Consolidation on the Undrained Bearing Capacity of Ring Foundations

The undrained bearing capacity of ring foundations has received significant attention from researchers, but most of the reported studies do not reflect the effect of consolidation due to preloading. In this work, we investigated the postconsolidation undrained vertical capacity of ring foundations resting on nonhomogeneous clays using finite differential analyses and the modified Cam-clay constitutive model. The results are presented in nondimensional form and were compared with data available in the literature. The coupling influences of the internal opening of the foundation, the magnitude of the preloading, the duration of the consolidation, and the initial overconsolidation ratio of the clay were all considered. A methodology based on approximating expressions that captured the numerical results well is proposed as a way of predicting the undrained capacity gain of ring foundations for any degree of preloading and consolidation.