Characteristics of Liquefaction Resistance for the Saturated Silty Soil Ground Treated by Compacted Gravel Pile Composite Foundation

Based on Beijing-Shanghai high speed railway, the numerical simulation mainly researched on the seismic behavior for the saturated silty soil ground, which was treated by compacted gravel pile composite foundation. It has been analyzed that the region of liquefaction distribution and the transferring rule of excess pore water pressure (EPWP) under a series of input acceleration seismic loads in the treated and untreated foundation. The research results indicate that the untreated saturated silty soil ground is almost whole liquefaction when the amplitude of input acceleration is more than 0.15 g. While for compacted gravel pile composite foundation, out of treated region is less liquefaction when the amplitude of input acceleration is 0.15 g, with the increasing of input acceleration, liquefaction region is further more and gradually expands to the inner soil between piles, and compacted gravel pile composite foundation is only partial liquefaction when the amplitude of input acceleration is 0.25 g. EPWP is increased with the increasing of input acceleration seismic load, and the increasing of EPWP can be restrained effectively by compacted gravel pile composite foundation, and the quality of liquefaction resistance is improved. The design of compacted gravel pile composite foundation can satisfy the seismic requirements of Beijing-Shanghai high speed railway under the condition of 7 degree seismic fortification.