Load-sharing mechanism of piled-raft foundation: a numerical study

Responses of the piled-raft foundation are complex due to the combined working and the existence of load-sharing mechanism between piles and raft. A clear understanding of this mechanism leads to optimization of the design of the foundation. This paper presents numerical studies on the load-sharing mechanism characterized by the load-sharing ratio under using different numbers of piles and broad ranges of values of pile spacing, pile length, settlement of the piled-raft, and the depth of the raft base based on the finite element method constructed in PLAXIS 3D. The results show that the load-sharing ratio of the piled-raft increases significantly when increasing the value of pile spacing, the settlement of the foundation, and the depth of raft base, and decreasing the number of piles. This paper also introduces the stiffness modification ratios of piles and rafts. Interestingly, these stiffness modification ratios and the load-sharing ratio can be nicely collapsed on a master curve as a function of a dimensionless number which is defined as a ratio of pile stiffness and raft stiffness for each case of pile configuration. These scalings provide clear evidence for the unified description of the key parameters to control the load-sharing mechanism of the piled-raft foundation.