NUMERICAL SIMULATION ON THE SETTLEMENT TIME PROPERTY OF PILE-SLAB COMPOSITE FOUNDATION

In order to provide the scientific basis for design of CFG pile in high-speed railway, the settlement time property of pile-slab composite foundation is studied by means of 3-D numerical simulation methods considering Biot consolidation theory in the Fengyang section of Beijing-Shanghai high-speed railway. The results prove that: (1) 3-D numerical simulation considering Biot consolidation theory can commendably study the settlement time property of pile-slab composite foundation; (2) settlement increases over time, consolidation settlement mainly occurs in the underlying soft layer, and its affected depth is about 1.5 times of the pile length, accounting for about 90% of total settlement; (3) settlement significantly decreases by the power function as the pile length increases, and decreases by the power function as the pile diameter increases, and increase by the polynomial function as the space between the piles increases, and remarkably increases by the linear function before piling and very remarkably decreases by the polynomial function after filling as the preloading soil increases before piling; (4) as for the controlling of settlement, the pile length is the main control parameter, and the pile diameter takes about 0. 4m better, and the space of the piles takes about 5 times of the pile diameter better, and the preloading soil of 3m and about 6 months is appropriate before piling.