Settlement prediction of axially loaded piled raft foundations using advanced finite element analysis

Piled raft foundations are an advanced engineering solution designed to improve safety against a potential bearing capacity failure or more importantly to mitigate the risk of excessive total or differential settlement and the generated flexural stresses in the raft. In a piled raft system, a concrete raft acts as the primary load-distribution platform and piles are installed into deeper, more stable soil strata to control settlements. This design approach facilitates economic design without compromising the safety and performance of the foundation. Several simplified methods are available in the literature to estimate piled raft settlement; however, these methods possess limitations in terms of simulating the realistic soil-structure interaction and load-sharing behaviour among the piles and the raft in complex ground conditions particularly for soils with highly variable strength and stiffness parameters. In addition, these methods lack accuracy when dealing with non-typical pile arrangements or piled raft geometries. This study utilises the finite element method as an advanced tool to investigate the non-linear load settlement behaviour of a piled raft. A series of parametric studies have been conducted to explore the soil-structure interaction problem and identify the impact of influential parameters on piled raft settlement, including piled raft geometry, pile spacing, number of piles and the depth to a stiff layer. The findings from this study offer valuable insights into the design and analysis of piled raft foundations, as well as a deeper understanding of the load-sharing mechanisms within these systems.