Study On Vibration And Rail Corrugation Of Subway Vibration-Reduction Track Structure

With the rapid development of urban rail transit,rail corrugation in subway is becoming more prevalent.It not only aggravates the interaction between wheel and rail,but also causes vibration and noise of vehicle-track system,which affects riding comfort and is also closely related to the safety of train operation.Therefore,it is the great practical significance to study the cause and influence factors of the rail corrugation.The elastic-rigid coupling dynamic model of vehicle-track system and elastoplastic wheel/rail contact model are established in vibration-reduction tracks,and the-vibration features of track structure and wear characteristics of rail are in depth studied.The related factors for the formation of rail corrugation are analyzed,which will provide reference for the systematic study of the mechanism of rail corrugation.The research content and main conclusions are as follows:1.According to different types of metro vibration-reduction tracks,three-dimensional solid finite element model of steel spring floating plate track and ladder-type sleepers track structure are built respectively.Combined with the method of elastic treatment,the response characteristics of each component are calculated by dynamic simulation.In addition,under two conditions of the absence of track excitation and the United States five track excitation spectrum,the vibration characteristics of vibration-reduction tracks are analyzed and compared with the field measured results in order to prove the correctness and availability of model,which provides a model basis for the subsequent discussion of the relationship between the vibration characteristics of the track structure and the rail corrugation.2.The influence of fastener stiffness,size of vibration damping device under rail as well as stiffness of damping device and installation spacing under sleeper are studied on vibration frequency and mode of steel spring floating plate track and ladder-type sleepers track structure.The results show that the increase of fastener stiffness makes the peak frequencies of both sides of rail and vibration damping device under rail increase.Vibration degree of the middle and high frequency section in track structure can be effectively controlled by adjusting the vertical stiffness of fastener,while the increase of the vertical stiffness of the steel spring and the damping pad makes vibration frequency of track increase in a smaller frequency range.Besides,the change of track parameters has great influence on the vibration frequency of each structure close to it,but it has little influence on the vibration frequency from the far ones.According to the changes of the parameters of the lines and track structure,the characteristics of the track vibration and the wear of the rail are analyzed so as to pave the way for the related research of rail corrugation.3.Combined with the finite element and dynamic software,the elastic-rigid coupling dynamic model of vehicle-track system is built.Especially in ordinary track,steel spring floating slab track and ladder-type sleepers track structure,the frequency characteristics of variable states in rail and vibration damping device under rail are compared.In addition,the relationship between vibration characteristics of track structure and rail corrugation is studied.The results show that,there is a more obvious resonance phenomenon of inner rail contacting respectively with the floating slab and ladder-type sleepers.Under the circumstance of both sides of rail and vibration damping device under rail is together relative to ballast bed,the vertical bending vibration and the same side antisymmetric vibration are carried out on the specific frequency.At the same time,it is also presented by an unequal longitudinal stretch.What is more,the partial load caused by the superelevation of the curve makes the inner wheel play a constraint effect,and the vibration frequency reduction of the track structure leads to a variety of coupling bending vibration modes in the track,which complicates the situation of bending vibration in track system greatly.4.Based on the wheel/rail contact theory,the evaluating indicators such as wheel/rail force and wear index are used to explain the causes of rail corrugation.First of all,in two types of vibration-reducing track structures,the peak points distance of interaction force on wheel/rail and wear index shows various wear characteristic,such as a fixed wavelength cycle and alternate variety wavelengths,and it has obvious characteristics of periodic change.Secondly,for the actual problem of rail corrugation on the small radius curve,the influence of the curve condition and the track excitation on wear characteristics is studied.The results show that the non-uniform wear in the longitudinal direction of the small radius curve line(R300m)is mainly related to the characteristics of curve radius.It is not related to the random characteristics of track excitation in the conventional magnitude range.On the contrary,especially in relatively large radius curve,the non-uniform wear is mainly related to random features of track excitation.Finally,by calculating the stress distribution of wheel/rail contact,it is found that the wheel/rail contact stress of different special positions in the longitudinal direction exceeds the yield limit of rail material,and the peak stress leads to plastic deformation and indentation easily.5.The cause of rail corrugation is further demonstrated by comparing the vibration and wear characteristics of vibration-reduction track and ordinary track under the same curve condition.The results of the study show that there is a significant difference in the resonance frequency band between the ordinary track and the vibration-reduction track on the vibration characteristics.In terms of wear characteristics,the rail wear index of the two types of vibration-reduction track has a fixed peak-point separation distance,showing periodic variation characteristics,while the ordinary track does not exhibit obvious regularity characteristics.At the same time,the ordinary track does not have the conditions of rail corrugation with fixed wavelength.In addition,the simulation result is close to the wavelength distribution range of the field test,which demonstrates the rationality of simulation model and calculation results.