FEA Of Settlement Of High-Speed Railway Ballast-less Sub-grade On Composite Foundation

With the great development of the high-speed railway, the requirements of smoothness and comfort become more important. The subgrade are needed to have less settlement after acceptance, less differential settlement, less deformation under dynamic loads, and have greater stability. Effective treatment on soft soil are demanded when the constructions of subgrade of railway are on soft soil, this increases the difficulty of the control of settlement. As the general form of rail in high-speed railways, Ballastless Track on soil subgrade are totally new in China, having no experience to obey. The dynamic response of the subgrade and foundation under this structure is an important and difficult point in design.Based on the Beijing-Tianjin Intercity Express, the structure behavior of the CFG pile composite foundation are studied using the FEA software in this paper. Soil are treated as the elastic-plastic constitutive model, the slab ,the subgrade and the foundation under them are considered as a system, the rail load ,whether static or dynamic are worked directly on the slab. The nonlinear FEA software- MSC.Marc are used to discuss the situations of different pile length and distances, and the response under static and dynamic loads. At last this paper inferred the suitable length of piles and the distances among them fit for the geological materials this paper supplied, and also analysed the differences between static and dynamic response.