Numerical Analyses of Piled Raft Foundation in Soft Soil Using 3D-FEM

In recent years, the piled raft foundation has been widely accepted as one of the most economical methods of foundation systems. To evaluate the possibility of implementing this system in a very soft ground condition, this research performed the numerical analyses of the piled raft and pile group foundation systems for low-rise (8-storey) and high-rise (25-storey) buildings with 1-2 basement levels in subsoil conditions of the central part of Thailand, using three-dimensional Finite Element Method. The soils are modelled with Hardening Soil model and Mohr-Coulomb model. Evaluations of the performances of piled raft foundation, i.e., the load sharing ratio of piles, settlement behaviours in both the foundation system and the raft are discussed in comparison with those of the pile group. With limited cases considered and assumptions in this study, the results suggest the potential of using the piled raft system for low-rise building having 2 levels of basement. With this condition, the raft can carry some bearing capacity from pile around 20%. However, the safety factor of piles in the foundation design seems to play a key role on the effectiveness of the piled raft foundation as well and should be further studied.