Behaviour of Piled Raft Foundations
Research into the behaviour of large piled raft systems is being carried out, as the inclusion of the raft in the bearing capacity calculations and in the deformation assessment, can mean substantial savings in the cost of the foundation.
Analysis involves calculating the interactions that are occurring between the raft and the piles or pile-to-pile interaction. The interaction calculations have been the focus of research using different methods such as the Boundary Element Method or the Finite Layer Method.
Pile behaviour can also be treated as non-linear, if it is assumed that interaction factors remain constant during non-linear pile behaviour.
Finite layer techniques allow lateral or horizontal loading of the piled raft to be analysed, as well as vertical loading (or combinations of both). The advantage of the method is that the soil does not have to be discretised as for finite element analysis, and this saves time in preparing data for analysis as well as run time.
Shown below are results of analyses showing the pile locations and deformation contours or the deformed mesh of the raft for some piled raft analyses performed previously.