Research On Straight Switch For Continuously Welded Rail In Urban Rail Transit

Urban rail transit is the main part in urban public transport. It has many advantages such as large traffic volume, prompt, convenience, security and high efficiency. It is the primary way to solve the problem of traffic jam in large cities, and the situation of passenger traffic in large cities can be improved. Its function can't be replaced by other means of communications. Therefore urban track transit is developed in many countries. Urban rail transit is different from national railway, so its own characteristics should be combined with when the track structure is researched. The research will be of great significance for the development of urban rail transit in our country.As a kind of important track structure, switch is technical puzzle of continuously welded rail (CWR) track across section. In our subway line, there are Single point, Single crossover, Scissors crossing, etc. No.7, 9, 12 switch is more often, and there are two forms of turning part: straight switch and curve switch. Although movable joint is at heel end of straight switch and the stability is not ideal, the damage is prone to occur, with low running speed on urban rail transit, the merits are long service life, small trip force and single-point traction, and its structure is simple, left and right hand turnout is universal, reduce the quantities of sparse on job site, so it is widely used on urban rail transit. As a kind of common equipment on throat near metro station, crossing track crossover can be joined in a butt to butt way, and the floor area can be decreased obviously, so it is widely used in our country for the existed railway and the railway in construction. Analysis the regularity stress and displacement, and research design theory and method, can be used to supervise turnout design, laying, maintenance and repair. So far, the regularities of stress and deformation have not been studied, so in this paper, research has been done on No.9 straight switch of crossing track crossover.Aiming at the characteristics of crossing track crossover in ballastless track of viaduct and railway on the ground in urban rail transit, using FEM of Beijing Jiaotong University, longitudinal and lateral coupling model of straight switch in crossing track crossover is established. The stress and deformation of crossing track crossover are analyzed. The results are compared with crossing track crossover in ballastless track on subgrade and the crossing track crossover of elastic flexible curve switch, and the common and different performances are analyzed. The calculation of cancelling buffer area for the condition of straight switch on bridge is proposed. The main influencing factors on stress and deformation of crossing track crossover in ballastless track on bridge are analyzed: rail temperature, fastening resistance, spacer block, bridge temperature, pier stiffness, layout of bearings, span types, etc, and tentative to analysis the reason of these regularity. Based on the analysis results, suggestions are put forward for design of crossing track crossover in ballastless track on bridge.