LAUSR

Abstract It is widely accepted that the presence of compressible layers beneath pile groups can substantially increase the settlement of a pile group. Furthermore, as the size of the pile group increases this effect is magnified and further complicated by the load distribution across the pile group. A number of simplified methods, such as the equivalent raft or equivalent pier method, are often employed to estimate the settlement of pile groups founded over a compressible layer, however, such methods can lead to both overly conservative and un-conservative results and large variations in results between methods. More recent methods have explored the use of power law functions or energy principles to analyse piles and pile groups in non-homogeneous soil conditions, however, these methods can be difficult to apply in practice. With the availability of modern computers and the advancement of commercially available numerical analyses packages, it is now possible to use the finite element method to analyse pile groups overlying compressible soil layers in order to better understand this problem. This technical note presents some initial results and associated design charts based on the finite element method to provide preliminary estimates of settlement of pile groups overlying compressible layers. Some dimensionless design charts are provided for a range of commonly encountered geotechnical conditions and pile group geometries.