Study Of Doubleblock Ballastless Track Causing By Subgrade Differential Settlement

The stiffness of ballastless track's slab or roadbed slab is big ,so the basis differential settlement will be revealing significant effects on ballastless track's stress. There is different extent model reduction in Chinese designing of ballastless track, generally no design was given in foundation settlement , the importance of differential settlement for the track structure was neglect at the same time, therefore ,it can not reflect the structure actual stress of ballastless track overall. The paper regarded twin-block ballastless track of soil subgrades under differential settlement as the research object,established a mechanical analysis model of beam-slab, and have an systematic analysis of its mechanical properties.This paper use Finite Element Software to analysis double-block ballastless track of soil subgrades under differential settlement as the research object: Rail is simplified as flexible point Euler-beam with unlimited length. Fastener will be simplified to linear springs . Roadbed slab and supporting layer which thickness size is far smaller than the length and width size, according with the elastic thin slab structural characteristic, are simplified as Plate-Shell element . And base support is simplified as diaphragm flexure. In this article, we assuming that the change of foundation deformation by cosine curve, then according this theory to simulating calculatin.This paper mainly introduces the structural design methods of double-block ballastless track on the roadbed, and the calculating method of ballastless track under soil subgrades when considering differential settlement . The paper includes the following parts: The feasibility of using rigid foundation mathods as a simplified calculation of subgrade under differential settlement is proved through comparative analysis. Reinforcement design for double-block ballastless track under soil subgrades according to allowable rail bending stress method ,then presents the Limit of differential settlement. For various foundation stiffness, the paper compares the impact of soil subgrades under differential settlement on the track superstructure ,in order to reache the best and reasonable methods by technological and economical way. At the same time ,this paper analysis the influence of soil subgrades under differential settlement on the track superstructure when supporting layer failuring.