| With the continuous improvement of the road network of high-speed railways,high-speed railways have become the preferred means of transportation for travel,and higher requirements have been placed on the safety and smoothness of trains during operation.In the course of railway operation,the uneven settlement of the road-bridge transition has always been an important factor affecting the smoothness of the track and the comfort of riding.Although a lot of research work has been done in the early stage,and the design scheme of the road and bridge transition section is also gradually improved,it is still necessary to take into account various irregularities in the operation process,conduct more in-depth theoretical research,and achieve a deeper level of transition section design optimization to ensure the quality of operation.To this end,the paper mainly conducts the following research work:(1)Construct a finite element model of the vehicle-track-transition system for power system analysis.Based on the vehicle-track coupling dynamics,a vehicle-track-transition system finite element model is established.The model is used to simulate the dynamic response of vehicles and tracks when a high-speed railway passes through the road-bridge transition.The corresponding dynamic evaluation of the vehicle and track is combined with the corresponding evaluation indicators.(2)Investigate the sensitivity of the parameters such as the stiffness of the fastener,the length of the transition section and the filler characteristics to the dynamic response of the ballastless track.Through the control variable method,the stiffness of the fastener,the length of the transition section and the elastic modulus of the filler are taken as variables into the model for simulation.By comparing and analyzing the simulation results,it is found that the stress and vibration of the track structure are greatly affected by the vertical stiffness of the fastener,and are less affected by the lateral and longitudinal stiffness.When the vertical stiffness of the fastener is 30 kN / mm,the track can be guaranteed.Sufficient elasticity makes the track structure have sufficient smoothness,and does not cause excessive stress on the track structure and reduces track life.The length of the transition section also affects the operation of the vehicle and the vibration of the track structure.As the length of the transition section increases,the wheel-rail force,wheel load reduction rate,and derailment coefficient all decrease to a certain extent.When the length of the transition section reaches 20 m,the increase in length will stabilize the vehicle and track vibration.The characteristics of the filler in the transition section also have a greater impact on the dynamic performance of the ballastless track.Too small or too high the elastic modulus of the filler will adversely affect the vehicle and the track.When the elastic modulus of the filler is 130 ~ 150 MPa,it can ensure the smooth transition of the stiffness between the roadbed and the bridge to make the vehicle run safely and smoothly,while ensuring that the vibration of the vehicle track is at a relatively low level.(3)Research on comprehensive optimization design methods of fastener stiffness,length of transition section and filler in transition section of road and bridge.Taking the stiffness of the fastener,the length of the transition section and the filler as design variables,the vehicle's running safety and stability are constraint functions,and the vertical acceleration of the vehicle body,wheel load reduction rate,derailment coefficient,and vibration and displacement of each part of the track are used as the objective functions.To ensure that changes in design variables keep vehicle and track vibration and displacement at a low level without affecting the safety and stability of the vehicle's operation,and at the same time achieve the purpose of reducing engineering costs and workload of track maintenance.The resulting design variables become the optimization results... |
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