Study On Lateral Displacement Of Curved Ballasted Track On Bridge Considering Nonlinear Characteristics Of Track Bed

At present,many railway curved bridge tracks at home and abroad will have the problem of excessive eccentricity of the line beam,and after the maintenance,there will be a relatively large eccentricity of the line beam in a short time,which causes great inconvenience and huge economic losses to railway transportation.Therefore,it is necessary to study the eccentric development mechanism of ballasted track midline and bridge midline under the action of train,understand the influence of system parameters on eccentric distance,and thus develop better maintenance schemes.Therefore,taking the upward multi-span continuous reinforced concrete deck arch bridge of Shitai Line as an example,the track-bridge coupling model considering track-bed nonlinearity is established to explore the lateral eccentricity of the curved ballasted track.The main research work and conclusions are as follows :(1)The skeleton curve of lateral resistance and displacement of ballast bed was obtained by studying the mechanical properties of ballast bed.The Massing criterion correction method was used to construct the transient hysteresis curve of ballast bed according to the skeleton curve of ballast bed,and the curve relationship between lateral resistance and displacement of ballast bed at any time was obtained.Solving Nonlinear Dynamics of Track Bed with Newmark Method and Full Iterative Method.(2)Based on the principle of total potential energy with a stationary value in elastic system dynamics and the ‘set-in-right-position’ rule for assembling system matrices,a 60-DOF dynamic model of ballasted track is established.Taking the multi-span continuous reinforced concrete deck arch bridge on the Shi-Tai line as the prototype,an eight-span concrete solid-web curved arch bridge model is established,and the coupling matrix of track and bridge is established.The train is equivalent to the external load applied to the track-bridge model.Combined with the mechanical properties of track bed,the spring between the sleeper and the track bed is set to be nonlinear.The track-bridge nonlinear dynamic model of track bed is established.Finally,the vibration equation of track-bridge nonlinear coupling model under moving train load is solved by Newmark method and full iteration method,and the vibration response results of the system are obtained.(3)The influence of track-bridge model parameters with nonlinear characteristics of track bed on the dynamic response and eccentricity of trackbridge system is explored.The results show that the initial stiffness of sleeper and track bed,the external load of train and the yield strength of track bed have great influence on the vibration response,residual deformation and eccentricity of track-bridge system.According to the research results,a scheme to solve the lateral displacement eccentricity problem of railway curved bridge track is proposed : controlling the size of the external load of the train,limiting the train speed below 60 km/ h,doing a good job of maintaining the track,ensuring that the lateral resistance of the track bed does not deteriorate significantly,increasing the yield resistance of the track bed,and ensuring that the resistance of the track bed is above 15.92 k N.