Time And Frequency Analysis Of Vibration And Noise Characteristics Of Ballastless Track In High Speed Railway

At present,the high-speed railway ballastless track has been widely used in China's railway construction,but the environmental vibration and noise pollution problems caused by it have become increasingly prominent.In order to provide theoretical guidance for the vibration and noise reduction of the ballastless track of high-speed railway,it is necessary to study the mechanism and characteristics of distribution and propagation of vibration and noise.The existing researches on the vibration and noise characteristics of the ballastless track of high-speed railway were not enough.In this paper,the vibration and noise analysis model of the ballastless track of high-speed railway was established.The Characteristics in time domain and frequency domain of the vibration and noise of the ballastless track are deeply studied,and the coherence between vibration and noise of ballastless track are explored.The research in this paper can provide a theoretical reference for the structural optimization and the development of vibration and noise reduction measures of ballastless track system in high-speed railway.The main research contents and results are as follows:(1)A vibration and noise analysis model for the ballastless track of high-speed railway was established.Firstly,the high-speed vehicle-ballastless track interaction dynamics model was established based on theory of vehicle-track coupling dynamics.The time-domain spectrum of wheel-rail force was simulated,which provides reasonable and reliable excitation for the numerical analysis of vibration and noise of ballastless track.Then,the finite element-boundary element method was used to establish the analysis model of the vibration and noise of ballastless track.By comparing the calculation results of this paper with the measurements and simulation results of vibration and noise in high-speed railways at home and abroad,the modeling method and the model were verified.(2)The time domain and frequency domain characteristics of the vibration of the ballastless track in high-speed railway were analyzed.Based on the finite element model of the ballastless track vibration of high-speed railway,the harmonic response analysis method was used to analyze the transmission characteristics of the track vibration.The transient analysis method was used to simulate the time domain characteristics of the track vibration under the high-speed train load.The Fourier transform and one-third frequency transform of the time domain results were carried out to further analyze the frequency domain characteristics of track vibration under high-speed train loads.Studies have shown that the vibration of the rail and track slat decays along the longitudinal direction with the increase of the propagation distance,and the attenuation of the low frequency band is faster than the high frequency band,The vibration energy of the rail is mainly distributed in the frequency band of 600-3000Hz,and reaches a peak at a frequency of 1010Hz.The vibration energy of the track slab is mainly distributed around the frequency of 3000Hz.(3)The time and frequency domain characteristics of the noise of ballastless track in high-speed railway were analyzed.Based on the high-speed railway ballastless track noise analysis model and the vibration response of track structure,the transient boundary element method was used to simulate the time domain characteristics of the noise of the track structure under high-speed train loads,and the Fourier transform and one-third frequency transform were carried out to further analyze the frequency domain characteristics of the acoustic radiation of the track structure under high-speed trair loads.The research shows that the acoustic radiation of the track structure is attenuated with the increase of the propagation distance,and the near-field attenuation of the track structure is faster.The radiated noise of the track structure is mainly distributed in the frequency band of 600-3000Hz,and reaches the maximum at the pinned-pinnec resonance frequency of rail.The acoustic radiation of the track structure increases with the increase of the height in the observation area,and the attenuation characteristics with the increase of the distance are more obvious in the low frequency band(100-400Hz)and the high frequency band(at 1600Hz).(4)The coherence between the vibration and noise of the track structure under the high-speed train load was analyzed based on the coherence function analysis method,The research shows that the coherence of the rail vibration and the ballastless track radiated noise in the 800-3000Hz band is obvious,and the coherence of the track slat vibration and the ballastless track radiated noise at the frequency of 650Hz and the frequency band of 2000-3300Hz is obvious.When the distance reaches 15m,the coherence of the vibration and noise of the observation points is small.(5)The influence law of parameter on the vibration and noise characteristics of the track structure was analyzed.Based on the vibration and noise analysis model of the ballastless track of high-speed railway,the influence of key parameters such as fastene stiffness,fastener damping and fastener failure on the vibration and noise characteristic of the track structure was analyzed.Studies have shown that below 800Hz,the vibration of rails,track plates and the radiation noise of ballastless track structures increase with the increase of fastener stiffness.The vibration of the rail basically decreases with the increase of the damping of the fastener.The vibration of the track slab increases with the increase of the damping of the fastener.The radiation noise of the ballastless track decreases with the increase of the damping of the fastener.The vibration of the rail increases with the increase of the number of fastener failures.The vibration of the track slab decreases with the increase of the number of fastener failures.The radiation noise of the ballastless track basically increases with the increase of the number of fastener failures.