Research On Long-Term Mechanical Properties Of Continuously Welded Turnouts On High-Speed Railway Bridges

With the completion of high-speed railway construction and the operation stage of line infrastructure,under the long-term complex load,the track structure itself and the interaction between track-bridge will gradually deteriorate,resulting in great differences between the mechanical characteristics of track structure during service and those at the initial stage of design and construction.Moreover,there are many components of continuously welded turnouts on bridge,and its mechanical characteristics are complex,which involves continuously welded turnouts,jointless track on bridge,adaptability of bridge to turnout and other related issues.This kind of complex mechanical characteristic makes it necessary to pay more attention to the continuously welded turnouts on the bridge in the long-term service process.Based on the finite element software ANSYS and multi-body dynamics software UM,the static model and rigid-flexible coupling dynamic model of continuously welded turnouts on bridge are established in this paper.Considering the influence of bridge shrinkage and creep and complex load conditions on longitudinal mechanical characteristics of continuously welded turnouts on bridge during service,the dynamic response of continuously welded turnouts on bridge under different operating conditions during service is studied,and the maintenance and management methods of continuously welded turnouts on bridge are discussed.The specific research work and results are as follows:(1)Establishment of static and dynamic model of continuously welded turnouts area on bridge.Based on finite element theory and rigid-flexible coupling method,the static and dynamic models of continuously welded turnouts area on high-speed railway bridge are established.At the same time,the longitudinal displacement-resistance constitutive model with hysteretic characteristics is considered in the beam-rail interaction relationship,and APDL is used for secondary development,considering the timevarying relationship of beam-rail interaction,so that the model can simulate the longterm longitudinal mechanical behavior of CWR on bridges.(2)Static characteristics analysis of continuously welded turnouts on bridge during service.Based on the static model of continuously welded turnouts on bridge,the longitudinal mechanical variation of continuously welded turnouts on bridge under cyclic load,multi-load coupling and bridge shrinkage and creep during service is studied.Under cyclic temperature load,residual stress and residual strain are produced in continuously welded turnouts on bridge.Residual stress and strain increase with the increase of historical load peak value.With the decrease of longitudinal resistance of fasteners in service,the peak value of longitudinal force of basic rail of continuously welded turnouts on bridge will gradually decrease,while the peak value of displacement of point rail and center rail will gradually increase.Under the multi-load coupling action,the braking/starting load will have great influence on the mechanical state of continuously welded turnouts on the bridge during service,while the train load has little influence.Under the action of bridge shrinkage,the initial stage of bridge shrinkage has a great influence on the mechanical state change of continuously welded turnouts on the bridge,and the influence gradually decreases with the increase of service time;The longitudinal mechanical characteristics of continuously welded turnouts on bridge are affected by the action of bridge creep arch,which mainly affects the position of beam joint of bridge,but has little influence on the middle part of bridge,and its value has a linear relationship with the amount of bridge creep arch.(3)Dynamic characteristics analysis of continuously welded turnouts on bridge during service.Based on the dynamic model of continuously welded turnouts on rigid-flexible coupling bridge,the effects of stiffness change of fastener system at different spatial positions in turnout area and shrinkage and creep of bridge on dynamic response of turnout-bridge-vehicle during service are analyzed.In the switch area and the switch area,the change of continuous fastener stiffness has the greatest influence,the change of integral fastener stiffness takes the second place,and the change of single fastener stiffness has the smallest influence under the change of fastener service performance.The section with the top width of center rail from 0 to 50 in the switch area has the highest sensitivity to the change of fastener service performance,which can be used as the key area of daily maintenance and management.Under the action of bridge shrinkage and creep,it mainly has great influence on the dynamic indexes of train passing through the connection area,but has relatively little influence on the dynamic performance of the switch area and the switch area.(4)Calculation method of locking rail temperatureCombined with the analysis of longitudinal mechanical characteristics of continuously welded turnouts on bridge during service period,based on the existing detection methods,the calculation method of locking rail temperature is modified.A multi-input and single-output model is established by using long-short-time memory network(LSTM)to predict and calculate the residual stress of continuously welded turnouts on bridge.The full text contains 161 figures,18 tables,and 102 references.