Numerical analysis of composite piled raft with cushion subjected to vertical load

摘要

In order to mobilize shallow soil to participate in the interaction of piled raft foundation sufficiently, the authors extended the concept of piled raft to a new type of foundation named composite piled raft. In the system of composite piled raft, the short piles made of flexible materials were used to strengthen the shallow soft soil, while the long piles made of relatively rigid materials were used to reduce the settlements and the cushion beneath the raft was used to redistribute and adjust the stress ratio of piles to subsoil. Finite element method was applied to study the behavior of this new type of foundation subjected to vertical load. Influencing factors, which include ratio of length to diameter and elastic moduli of piles as well as thickness and elastic modulus of cushion, were studied in details. Load-sharing ratios of piles and subsoil as well as foundation settlement were also investigated in this paper. The conclusions had been successfully applied to some practical buildings in the coastal cities of China. The validity of the numerical results was examined through a seven-story building observed in situ.