Study On Noise Reduction In The Subway Station

With the rapid development of subway lines in China,the subway noise problem has become increasingly significant.Now the researches on subway station noise are mainly focused on subway platform noise,but the researches on the noise in the non-platform are little.In this area,the noise sources are widely distributed,harmful tot passengers and staffs and cannot be ignored.In the thesis,the noise reduction plan to a platform in a subway station is given being based on the test and the simulation results.In view of the above problems,noise is measured in the platform and non-platform area of the subway station,and the main noise sources are analyzed.The platform when the train enters the station is modeled using the software EASE.The spatial distributions of the noise in the platform are calculated and compared with the measured results.The sound absorption and noise reduction plan of the platform is made,and the expanded perlite is selected as the sound absorption material in the platform.The sound field in the platform with sound absorption is simulated,and noise reductions and the reasons affecting the noise reductions are analyzed.The main conclusions are as follows:The sound pressure levels in the non-platform area the subway station are below 80 d B(A)of the limit.In this area,the noise is mainly affected by the noise source nearby.The main noise sources are the escalator noise,the broadcast noise,the fan noise of security devices,the passenger flow and the fan noise in the consulting room.The sound pressure levels from low to high noise as follows: the escalator,the security fan,the corridor,the security exit,the stair and the consulting room.When the train enters and leaves the station,the sound pressure level of the platform are above 80 d B(A),and the main noise sources are the electromagnetic noise of the motor and the broadcast sound.When the train enters the station without sound absorption,the sound pressure levels in the platform near the train side are much higher than that far away from the train side.In the simulations,the sound pressure level at the side near the train entering the station is 20 d B(A),and in the test,the sound pressure level at the side near the train entering the station is 15 d B(A).This is similar with noise in the platform with sound absorption.The average noise reduction is 0.83 d B(A)near the arrival side of the train,which is smaller;the average noise reduction is 6.95 d B(A)far away from the arrival side,which is larger.This is mainly because,The sound source isbroadcast and motor,which are arranged at the ceiling and PSD of the platform,the direct sound is dominate near the train entrance side,and the reverberation sound is mainly far away from the train entrance side.So the noise reduction at the side close to the train entering the station is smaller,and the noise reduction at the side far away from the train entering the station is larger.