Numerical Simulation on the Post-Construction Settlement of CFG Pile-Slab Composite Foundation in High-Speed Railway

Abstract

Based on typical volume element and 3D FEM model established,this paper is intended to analyze the post-construction settlement of high-speed railway CFG pile-slab composite foundation and its affecting parameters by means of numerical simulation.The results prove that there is evident downward punching in the bottom of the pile while in the top of the pile there is less evident upward punching due to the minor thickness and large modulus of cushion.The increase of pile length,working as one of the main decisive parameters to affect the settlement,can effectively decrease the post-construction settlement.When the pile modulus greater than 10 GPa keeps increasing,it will exert minor decreasing effect on the post-construction settlement.Within the range of the pile diameter 3 to 6 times wide,it is advisable to set the space between the piles by wider pile diameter range in that there are no significant changes of the post-construction settlement within this set space.Furthermore,it helps to cut down the cost and facilitate the construction.Cushion of certain thickness(0.2～0.4 m) and modulus(120～200 MPa) can effectively regulate the punching of pile and reduce post-construction settlement.Reinforced concrete slab with its suggested thickness no less than 0.4 m works on post-construction settlement the same way as pile modulus does.The embankment height is not the main decisive parameter for post-construction settlement.