Research On Surcharge Pre-loading's Effect On Settlement Characteristics Of Compound Foundation In West Ji'nan Railway Station, Beijing-Shanhai High Speed Railway

China has entered the times of the rapid construction of high-speed railway network, and many passenger-lines have started construction.High-speed rail requires not only high strength subgrade, but also the high control of the settlement. We take advantage of part of the CFG piles and PHC piles to process Beijing-Shanghai High Speed Railway foundation, and use preloading to deal with road basic body and the foundation to achieve the specifications of the foundation settlement.This research project bases in "Study on Settlement Characteristics of Compound Foundation of the West Ji'nan Railway Station in Beijing-Shanghai High Speed Railway "of China Railway twelfth Group Co.,Ltd. Based on the purpose,the paper ansyses settlement the sate of plates, layered magnetic settlement gauge, bore gauge and measured excess pore pressure,and get the Variation of surbgrade settement, the layering settement, pale ane soil stess and excess pore water presuress,which is evaluated for future works:(1) It has completed the settlement of composite foundation for 40%of the total,unless upload process was short,and during the uninstall process,it will occur composite foundation rebound, rebound rate of about 10% of the total settlement;(2) The maximum excess pore water pressure occurres in the pre-compacted soil after the 30 or so,excess pore water pressure in the subsequent peak will occur within 30 days of the rapid dissipation;(3) Increase with time, pile-soil stress ratio increases, we can see the top of the pile load is gradually transferred to the soil, the pile-soil stress ratio will be reduced accordingly, during the unloading process.