Numerical simulation of composite foundation using pile-supported and geosynthetics-reinforced cushion with variable stiffness

The geogrid and geocell with high tensile strength are meant to reinforce the mixture of natural gravel and recycled concrete aggregate made of the soild waste of construction. The reinforced cushion with variable stiffness is constructed by adding moderate cement, lime or fly ash to the reinforced mixture, which can be adopted as the flexible raft to replace the concrete raft of pile-raft composite foundation. The finite element numerical model is established for comparison investigation. The results indicate that through the tensioned membrane effect and flexible raft effect, the geocell-reinforced cushion plays an important role in mobilizing the bearing capacity of the pile wall, decreasing the settlement of the surrounding soil and improving the pile-soil stress ratio. The working performance of the geocell-reinforced case can be better improved by increasing the modulus of the cushion. The thickness of the reinforced cushion should not be too thick.