Passenger Special Line Of Cfg Pile Composite Foundation Settlement Characteristics

High speed running of a train needs a smooth and stable track subgrade. As the foundation of track structure, the subgrade should maintain the designing parameters within a standard under the running condition, and this means that a high quality of stability for the settlement of subgrade is needed. Current study indicates that if the roadbed, filling material of roadbed body and compaction standards can be satisfied, the elastic deformation, plastic deformation in Train traffic and the settlement and compaction of roadbed filling is limited and controllable. the key point of controlling the settlement and deformation of the roadbed is to control the settlement of foundation.This article systemically studied the settlement of high-speed railway composite foundation of CFG piles both by theoretical method and numerical method. The contents are developed as following:(1)Summarizes current method of calculating composite foundation settlement, lists the applicability and characteristic of these methods separately according to the multiformity.(2)Certifies that because of the ambiguity in selecting composite module, when calculating the settlement of composite foundation of CFG piles with the method of composite module, it is deformation modulus of CFG piles should be selected as composite module of the composite foundation.(3)Corrects existing formulas of the composite foundation of CFG piles, and obtains formulas to calculate the settlement of composite foundation, by analyzing the settlement and deformation course of composite foundation of CFG piles, considering the pile-soil interaction, and introducing the calculating models of soil compression modulus which are changing with loads.(4)Compares the results of these methods with practical data. The results indicate that it is available to calculate pile-soil stress ratio in practical by using the fixed compression modulus method. However, it is more suitable to use various Compression modulus method to calculate the settlement of composite foundation of CFG piles.(5)Educes Optimal Design by use of Orthogonal Desing ExPernlinetartnin, and through setting up 3-D singled-pile model and 2-D mathematical grouped-piles model in ANSYS, analyzing the factors that influence grouped-piles' settlement such as the distortion modulus between pile-end-soil and pile-around-soil, intensity of pile, the depth and modulus of mattress layer, pile diameter and pile spacing, etc.