Studies Of The Continuously Welded Rail Track For Modern Trams On Three-way Bridges

Under the influence of urban municipal trunk roads and existing buildings,and in order to save urban space,reduce land occupation,transfer convenience and improve travel efficiency,the laying of modern tram rail seamless line on the three-way bridges is an inevitable design formula in the rapid development process of urban rail transit.Among them,the three-way bridges which is formed by the cross plane of the three viaduct lines,the two groups of 6# single open switches and a group of rhomboid cross combinations,and other factors such as the rhombus crossover switch and the small radius curve,put forward new challenges to the railway track seamless track laying on the three-way bridges.In this paper,a modern tram rail seamless track on a three-way bridges is taken as the research object.By establishing a finite element model which can consider line type,the influence of various factors such as the daily temperature difference of the bridge,the longitudinal resistance of the line,the amplitude of the rail temperature and so on on the interaction of the beam and rail on the seamless line on the three-way bridges is analyzed in detail.Some suggestions are put forward for laying a modern tram track CWR on the bridge.The main contents of this paper are as follows:(1)Based on the theoretical basis of the CWR on bridge,the particularity of the interaction between the beam and rail of the CWR on the three-way bridges is analyzed,and the finite element model of the beam rail interaction which can consider the line type is established,and the feasibility and accuracy of the model are verified.(2)Based on the finite element model of the modern tram rail seamless track on the three-way bridges,the influence of the train braking load,the train vertical load and the different broken rail position and the effect of the turnout on the bridge structure are analyzed,and the most disadvantageous mode of the external load is determined.(3)Based on the analysis results of the first two chapters,the interaction analysis of seamless track on the three-way bridges is carried out,and the influence of various factors such as the daily temperature difference of the bridge,the longitudinal resistance of the line and the amplitude of the rail temperature on the rail expansion additional force,the relative displacement of the beam rail and the force of the bridge pier and abutment force under the telescopic working condition are analyzed.The influence of the additional force of rail brake,the relative displacement of rail and the force of bridge pier and abutment force is studied under the working condition,and the influence of broken rail fracture value,the increment value of the longitudinal force of the rail longitudinal force and the increasing value of the bridge pier and abutment force is studied under the working condition,and the seamless line and the ordinary straight line bridge on the three-way bridges are compared.In the same condition,the longitudinal additional force,pier force,relative displacement of beam rail and rail fracture value are different under the same condition,and the reference value of longitudinal resistance design of the three-way bridges is given.(4)Based on the above calculation results and conclusions,the track of tram on the three-way bridges is optimized from the relative position of the switches on the three-way bridges,the form of the bridge span of the turnout,the layout scheme of the bridge support and the rigidity of the bridge pier and so on,and gives the proposal and three links of the layout of the upper switches on the three-way bridges.The recommended value range of bridge pier and abutment stiffness on bridge are also given.