| The diversified development of urban rail transit system has gradually become the general trend of urban rail transit development.The low-medium speed maglev transportation system suitable for urban rail transit has been put into commercial operation in many cities at home and abroad,which indicates that the technology of low-medium speed maglev system is becoming more and more mature.Due to the small suspension gap in the low-medium speed maglev train,the requirements for track structure are strict.Therefore,it is very important to study the key design parameters of low-medium speed maglev track structure.Based on the finite element model of low-medium speed maglev track structure,this paper studies the influence of key parameters of track structure on the vertical deformation requirements and the longitudinal crawling of track.After placing the high-performance grouting stuffing of the laboratory test specimen,some static experiments and fatigue test of the structure were completed.The key parameters static experiments of the low-medium speed maglev track structure were tested before and after the fatigue test,and the fatigue characteristics of the track structure were analyzed.Based on the hammer excitation test results of laboratory test specimens,the transient and modal simulation results of the 3D solid model are verified,and the influence of the design parameters of the track structure on the frequency of the key mode shape is studied.It mainly includes the following research contents and conclusions:(1)Through the static analysis of the vertical displacement of the three-dimensional solid model by changing the distance between the steel sleepers,the supporting position of the fastener under the steel sleepers and the stiffness of the fastener,the influence trend of the values of each parameter on the vertical displacement of the low-medium speed maglev track structure was obtained.According to the requirement that the maximum vertical displacement of magnetic pole surface of low-medium speed maglev track structure should not be greater than 0.6mm during the track static load test in the specification,the distance between the center of the coupler and the center line of the line should be greater than or equal to 0.44 m,and the suggested values of the vertical static stiffness of the coupler should be greater than or equal to 350 k N/mm.(2)Using formula calculation,solid element finite element model and beam element finite element model to analyze the expansion displacement of rail under the action of F rail temperature rise.Assume the longitudinal resistance and structural longitudinal resistance nonlinear load and unloading path.According to the model of beam element modal,the dissertation analyzes the rules of the displacement of the rail when braking force and temperature load are taken into account on the subgrade or on 25 m long track beam.The conclusion is obtained that reducing the longitudinal resistance of the joints and the vertical resistance of the fastener can effectively reduce the track crawling.(3)Laboratory tests of low-medium speed maglev track structures were designed to test the longitudinal resistance,clamping force and vertical stiffness of the two kinds of fastening assemblies before and after 3 million times of fatigue load.The variation rule of parameter test value under fatigue load of track structure is obtained,and measures up to the standard of fatigue change rate.(4)According to the force hammer test results of laboratory test specimens,the peak value of acceleration mobility below the frequency of 500 Hz was obtained,and the accuracy of the model was verified by comparing it with the transient analysis results of the three-dimensional solid model.Furthermore,the influence of the distance between the adjacent steel sleeper,the clamping stiffness of the fastenings,the value of the clamping force and the lateral distance between the center of the fastener and the center line on the frequency of the peak mode of the acceleration mobility is analyzed. |
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