Mechanical Characteristics Of CRTS? Ballastless Continuous Welded Rail On Long-Span Continuous Bridge

Ballastless continuous welded rail is widely used in high-speed railway both at home and aboard, due to its excellent stability, long service life and low maintenance workload. In recent years, more and more long-span continuous bridge used for railway have been or will be built across roads and rivers. Consequently, more attention is paid to the laying of ballastless continuous welded rail on long-span continuous bridge. Taking CRTS II ballastless continuous welded rail as main research object, mechanical characteristics of CRTS ? ballastless continuous welded rail on long-span continuous bridge are studied in both static and dynamic aspects. Besides, expansion length suitable for CRTS II ballastless continuous welded rail on long-span continuous bridge is calculated based on the intensity of the rail. The main research contents are as follows:Firstly, starting from the traditional theory of railway mechanics, three static analysis models of ballastless track are compared. And according to the interaction mechanism among rail, ballastless track and long-span continuous bridge, the static analysis model of CRTS ? ballastless continuous welded rail on long-span continuous bridge is established based on the beam-solid theory. Considering the factors such as temperature variation, changes of bridge structural parameter, stiffness reduction of slab and concrete roadbed as well as differential settlement, static mechanical characteristics of CRTS ? ballastless continuous welded rail on long-span continuous bridge are researched. Results demonstrate that in the design of CRTS II ballastless continuous welded rail on long-span continuous bridge, the actual temperature range in different regions should be considered and in order to increase the security and durability of the high-speed railway, the stress condition could be improved by reasonable support arrangement and support number. Besides, cracks of ballastless track structure on bridge as well as differential settlement should be tightly controlled to increase the service life and ensure the train running safely and comfortably.Secondly, three dynamic analysis models of ballastless continuous welded rail laying on bridge are compared. According to the interaction mechanism among train, ballastless continuous welded rail and long-span continuous bridge, the train is deemed to be a multiple rigid body system and the interaction relationship between wheel and rail is considered. And then, the dynamic analysis model of CRTS ? ballastless continuous welded rail on long-span continuous bridge is established. Modal analysis is carried out on the structure. Then dynamic response indexes of CRTS II ballastless continuous welded rail on long-span continuous bridge and influence of the train speed as well as trains running towards each other are researched. Results indicate that in the design of CRTS II ballastless continuous welded rail on long-span continuous bridge, attention should be paid to the stability along the bridge in the longitudinal as well as the calculation and monitoring of the dynamic response indexes for the component at the middle of the continuous bridge. Besides, the dynamic response indexes increase as the growth of the speed. Besides, when two trains run towards each other on the continuous bridge, the dynamic response indexes are greater than that when one single train runs on the continuous bridge.Finally, expansion length finite element model of CRTS ? ballastless continuous welded rail on long-span continuous bridge is established to analyze its influence on additional rail traction/brake stress and additional rail expansion and contraction force. With the results processed and fitted, relationship between expansion length and rail stress is derived. Then expansion length suitable for CRTS ? ballastless continuous welded rail on long-span continuous bridge is calculated based on the intensity of the rail. It is found that when the daily difference of girder temperature is 20?,25? and 30?, the maximum expansion length should be less than 404m,272m and 179m respectively.The research will provide reference for the design of CRTS ? ballastless continuous welded rail on long-span continuous bridge.