Control Of Noise Environment In The Subway Island Platform

With the acceleration of urbanization in China,the subway becomes the important facility of urban transportation.The subway platform as the main activity space should provide the good sound environment for passengers and staff.The train radiates much noise on pulling in or pulling out.Sound pressure level is larger in the platform without sound absorption materials due to longer reverberation time in this paper the sound field in a subway island platform is studied by the simulations and tests,noise reduction measurements are proposed and the study is theoretical basis for improving the platform sound environment.Firstly,the sound pressure level in the subway platform is measured on pulling in and pulling out,the reverberation time in the platform is measured by using the impulse response integral method,noise distribution in space and noise spectrum in the platform noise are analyzed,and is judged whether the noise is above the limit.Secondly,being based on the statistical energy analysis,the sound field model of the subway platform is modelled by using acoustic simulation software.The model is validated by comparison of the simulation and the test,and the noise energy flow distribution and the noise distribution are calculated and analyzed.Finally,three plans of sound absorption are proposed,and noise reduction is simulated and analyzed.The main conclusions are as follows:The sound pressure levels exceed 80 d B(A)in the platform next to the train on pulling in and pulling out,and the reverberation time in 500 octave band is 2.4s above the limit of 1.5s.At the same time sound pressure level in the platform next to train is 14.46 d B(A)greater than sound pressure level in the platform away from the train.The maximum sound pressure levels are at the way in on pulling in and way out on pulling out.The main noise sources are traction motor electromagnetic noise and broadcast noise.The traction motor noise energy flow bypasses the top of the platform screen door,propagates in the platform and attenuates rapidly.Broadcast noise attenuates rapidly in propagation as well.The sound field distribution on the planes at the heights of 1.2m and 1.6m from the platform floor are identical;the sound pressure levels in the platform next to the train and the track on pulling in are greater close to the traction motors,the pressure levels are lower far from the traction motors with the uniform sound field dominated by reverberation sound in three plans of sound absorption materials only lined in the track domain,only lined in the platform domain,and lined both in the domains,the sound pressure levels in the platform next to the train are 80.83 d B(A),80.26 d B(A)and 76.84 d B(A),and the reverberation time is 1.26 s,1.31 s and 0.96 s respectively.So sound absorption materials are lined both in the track and platform domains,and the sound pressure levels and the reverberation time requires the limits.