| Anti-seismic design on subway track is not a deeply researched subject internal, so this paper just brings forth a simplified calculating method to calculate the deformation of the track under seismic, and limits some deformation value coin with the cope. This paper starts from three sides when researched:simplify calculated methods by the lengthways of the tunnel; analysis on vibration of the track; analysis on vehicle-track dynamic interaction.(1) Track deformation analysis is assumed that track and tunnel structure is in common deformation, and make the displacement of the strata which the tunnel bottom in instead of the longitudinal deformation of the track when earthquake happened. Checking that what influence would different seismic intensity, strata and tunnel structure make to the deformation on above.(2) The reason for track vibration response analysis is that most subway structures are based on ballastless monolithic concrete bed, and the influence to track vibration comes from tie plate under track while the bed embed roadbed without elastic connection between them. Stiffness of the cushion decides deformation of the track. Another new shock absorption track structure such as floating slab structure, etc, is different from ordinary structure in damping effect because of the increase steel spring below ballast, so explained separately.(3) Vehicle-track dynamic interaction model. This is commonly used in orbit computation. The paper is mainly calculating influence from seismic to track structure, so it's also increased earthquake on this model and analyzes its corresponding reaction. The three methods explain the specific action of the track under seismic from simple to hard, and give different limited conditions to different action results for checking. Any structural design methods are aimed at certain design goal, and different design goal is to achieve different requirements, therefore, this paper also puts forward corresponding track structure anti-seismic performance requirements to adapt to the seismic design methods.Finally to illustrate the former method, according to some actual project material lists the calculation process and explained in detail of the process. This is not in specific engineering calculation of its seismic response, but I hope the seismic design method of anti-seismic design of metro could play a role, which can reduce earthquake damage in a certain extent of underground rail transportation engineering. |
