A Comparative Study On Vibration And Acoustic Radiation Characteristics Of Four Typical Subway Tracks

With the increasing development and improvement of the subway system,the issue of urban traffic congestion has been greatly improved,which provides great convenience for people's daily travel,but the noise of the subway has seriously affected the comfort of the passengers on the subway.Therefore,it is of great significance to effectively control the noise of subway to improve the comfort of passengers and the personnel engaged in the subway.In this paper,the research status of vibration and noise of various Metro tracks is summarized,and the vibration and acoustic radiation characteristics of four kinds of subway tracks are have been analyzed.The specific contents are as follows:(1)Based on the finite element method,the finite element model of ballastless track has been established,and the frequency response characteristics of the ballastless track have been analyzed.The correctness of the finite element model is verified by comparing the simulation results and experimental test.The vibration displacement of ballastless track in 230 Hz and 1020 Hz shows two peaks.(2)Based on the finite element method,the finite element model of the elastic short sleeper track,the elastic long sleeper track and the steel spring floating slab track has been established,and the frequency response characteristics of the three tracks have been analyzed.The results show that: At 12 Hz,the vertical vibration response of steel spring floating slab track is more obvious than that of the other three tracks.The peak frequency corresponds to the natural frequency of the floating slab.In the frequency range above 16 Hz,the vertical vibration response of steel spring floating slab rail is smaller than that of the other three tracks.In the frequency range below 100 Hz,the vertical vibration response of elastic short sleeper track and elastic long sleeper rail is larger than that of ballastless track.In the frequency range of 20~240 Hz,there are different peak frequencies of vertical vibration of four track types.In the frequency range above 300 Hz,there is little difference in vertical vibration displacement amplitudes between four tracks.(3)Based on the boundary element method,the acoustic boundary element models of the four tracks have been established,and the acoustic radiation characteristics of their rails have been analyzed.The results show that: The main frequency bands of the four commonly used radiated noise of Metro tracks are 315~1000 Hz.The sound power level of rail on ballastless track and steel spring floating slab track is 104.2 dB,the elastic long sleeper track is 103.9 dB,and the elastic short sleeper track is 103.6 dB.(4)Based on the boundary element method,the acoustic boundary element models of the four tracks have been established,and the acoustic radiation characteristics of their slabs structure have been analyzed.The results show that: The main frequency band of radiated sound power level of ballastless track slab is 315~1000 Hz,the elastic short sleeper track and the elastic long sleeper track is 100~250 Hz,the steel spring floating slab track is 200~250 Hz.The sound power level of slab on ballastless track is 65.1 dB,the steel spring floating slab track is 110.0 dB,the elastic long sleeper track is 106.0 dB,and the elastic short sleeper track is 104.4 dB.(5)The sound radiation characteristics of ballastless track,elastic short sleeper track,elastic long sleeper track and steel spring floating slab track have been compared.The results show that: The sound power level of the steel spring floating slab track is 111.0 dB,the elastic long sleeper track is 108.1 dB,the elastic short sleeper track is 107.0 dB,and the ballastless track is 104.2 dB.