A study of the piled raft foundation behaviour

In the recent decades, a new concept has evolved for the analysis and design of piled foundation which is the piled raft concept. This concept takes into consideration the proportion of load transmitted directly by the raft contact pressure in the piled raft foundation system. In the current work, a nonlinear three dimensional finite difference analysis was carried out to model several piled raft problems. Firstly, a back-analysis was made for two case studies to check the validity of the numerical modelling procedure performed by the author. Afterwards, a comprehensive parametric study was performed on a hypothetical square piled raft over three clay soil profiles with different degrees of stiffness. The variation was made in number of piles, length of piles and distribution of piles over the raft area. The variables were studied in terms of their effect upon the average settlement, differential settlement, load sharing between piles and raft and the piled raft working stress. The concluded observations from the parametric study can help the engineers in taking a logical path in an iterative design process for a piled raft foundation.