High-speed Railway Pile-raft Composite Foundation Settlement Characteristics And Pile-soil Stress Ratio Analysis

In order to meet the high speed railway safety and comfortable operation, roadbed post-construction settlement control standard strictly, foundation treatment method innovation, already from pile-nets structure development to the pile raft structure, and successfully applied to the soft soil of the Beijing-Shanghai high-speed railway and Shanghai-Nanjing Intercity. Based on the project of "High-speed Railway Ballastless Track Pile Raft Consolidation of Composite Foundation Characteristics and Settlement Control Mechanism Researc" supported by National Natural Science Foundation and railway technology projects about project of "research on Jinghu high-speed rail composite pile foundation for settlement control to reinforce soft foundation" supported by Railway Technology Program, through field experiment of soft foundation consolidation in zhenjiang section of Jinghu high-speed rail, this paper makes research on pile-soil stress ratio and settlement of pile-raft composite foundation in the process of high-speed railway filling, standing and preloading and unloading. Main conclusions of this paper are displaced as follows:(1)Through testing field monitoring, obtain the high-speed railway pile-raft composite foundation settlement and base reaction force in each construction stage of the measured data, this article analyses the law of development of settlement, pile-soil stress ratio in different position,and relationship between pile-soil stress ratio and settlement in pile-raft composite foundation;(2)Analyzes settlement and pile-soil stress ratio characteristics of the pile-raft composite foundation, and with high speed railway other foundation treatment way of comparison, the results show that the pile-raft composite foundation to make use of the bearing capacity of pile, settlement control effect is obvious;(3)Establish the pile-raft composite foundation3D numerical analysis model, and verifies the field monitoring the achieved test law, analyses raft thickness, cushion layer thickness, pile length, pile spacing, such as design parameters on the effect of pile-soil stress ratio.