Measured Characterisation of Vibration Source Strengths for Express Underground Lines
[Objectives]The existing prediction formula of vibration source intensity is only applicable to nor-mal-speed subways,and cannot be applied to the vibration source intensity characteristics of fast underground lines with a maximum speed of 160 km/h.[Method]The vibration characteristics of multiple sections of a coast-al city urban expressway were measured on site.The influence of vehicle speed,tunnel buried depth,curve and other factors on the vibration source strength was studied through data analysis.[Result]The vibration source in-tensity was between 71 dB and 80 dB at the speed of 90 km/h to 160 km/h in the straight(curve)line section.The vibration source intensity also increased with the increase of vehicle speed,and the vibration source intensity increased by 3.72 dB for every 20 km/h increase in speed.The vibration source intensity decreases with the in-crease of the buried depth of the tunnel.For every 10 m increase in the buried depth of the tunnel,the vibration source intensity decreases by 4.9 dB.In the same case,the vibration source intensity of the curve section(curve radius 1 850 m)is stronger than that of the straight section,and the value is about 7 dB.One year after the train was put into operation,due to the deterioration of the wheel-rail state,the vibration source intensity increased,and the difference between different trains was large.The monitoring data of seven months of a certain section were selected and analyzed.The vibration source intensity was relatively stable after the operation period was stable.[Conclusion]The vibration source intensity of the fast underground line is affected by many factors:it is linearly positively correlated with the train speed,the tunnel depth is linearly negatively correlated,the vibration source at the curve is stronger than that at the straight line,and the wheel-rail deterioration will also increase the vibration source intensity.
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