Time-settlement behaviour of piled raft foundations using infinite elements

Although there has been a great deal of attention paid to the settlement of pile groups and piled raft foundations, little attention has been paid to the time-dependent behaviour. In this paper, a full three-dimensional finite element analysis (making use of infinite elements) is carried out to estimate the rate of consolidation of piled rafts, and to calculate the magnitude of differential deflections and the associated moments that develop in the raft with time. It is shown that the settlement of a full scale structure can be reasonably predicted by use of the method and that the moment build up with time can be predicted. Comparison is also made with approximate methods that treat the piles, soil and raft as a single block of material with equivalent properties to the individual piles and the soil contained between them.