Experimental study on characteristics of vibration source and effect of vibration reduction measures in turnout of urban rail transit
There is inherent unevenness in the turnout area and its structural state is complex,which can lead to amplified environmental vibration and noise. In order to explore vibration generation mechanism and the influence of different vibration reduction measures on the vibration source characteristics in urban rail transit turnout areas,ordinary monolithic track bed,damping fastener,and steel spring floating slab turnouts were selected as experimental objects. Experimental tests and analysis were conducted on 5 sections for each turnout,including the front of the turnout,the wheel load transition area in switch,the heel of switch rail,the middle of closure rail,and the frog area. By testing the vertical and lateral vibration responses of tunnel walls at different locations in the turnout areas,vibration source characteristics were discussed from the perspectives of frequency domain,time-frequency domain,and Z-level vibration for different vibration reduction measures. The test results are shown as follows. The main frequency of the vibration source in turnout area with ordinary monolithic track bed is between 50 and 100 Hz,which is similar to that of the plain line. However,due to different support stiffness of the rails,there is a bimodal characteristic of P2 resonance frequency in the frog area. Since there is gap in the frog,high amplitude of 50～200 Hz vibration response of the tunnel wall can be observe,leading to the vibration source increases by 3～5 dB compared to other sections. Although there is wheel load transition in the switch area,the tunnel vertical vibration does not show significant intensification. Lateral vibration in turnout cannot be ignored. Lateral vibration of the tunnel wall in damping fastener section is even higher than the vertical vibration. Both vibration damping fastener and steel spring floating slab track can reduce tunnel wall vibration above 50 Hz,but damping fastener reduce the P2 resonance frequency of the un-sprung mass-turnout to 40 Hz. This can result in a higher vibration response peak at this frequency region. By comparing the VLmax and the VLzmax,it is found that the vibration reduction capacity is relatively low for damping fastener in turnout area,while the vibration reduction of steel spring floating slab is around 15 dB. The experimental research results can provide reference for the vibration control of urban rail transit turnout areas.
万方数据
维普
