| With the development of urban transportation in our country,people’s travel modes are becoming more and more diversified.In addition to road transportation,there are intercity railways that run through the urban areas,or subways,trams,and other urban rail transit in cities.At the same time,in order to increase the efficiency of transportation,various traffic modes have appeared in various forms such as elevated sections and underpass tunnel sections.This makes multi-mode complex traffic conditions appear at some traffic nodes,serious noise pollution often occurs at these traffic nodes.The noise control of these traffic nodes is very difficult because of the high complexity of the sound sources,need to find major noise sources for key management.This paper selects a certain transportation node area in Chengdu for research.The transportation mode in this area is extremely complex,including subway,intercity railway,tram and road transportation.At the same time,the subway is connected to the elevated via a tunnel through a curved slope ship trough section.The intercity railway is in the elevated section,trams are in the form of ground,and road traffic includes tunnels and ground forms.By monitoring the noise of traffic modes with monitoring conditions and monitoring the noise of sensitive buildings,analyzing the noise characteristics of each traffic mode in the area,combining with Cadna/A software,the noise model of the area is established,and designed a set of noise reduction schemes according to the characteristics of the noise in this area,finally got the results and conclusions as follows:1.The noise of the ship trough section of the subway has its own unique frequency characteristics,and the main contribution frequency range is 63-4000 Hz.Compared with other studies,the noise of the ship trough section of the subway is higher in sound pressure level in the frequency range of 63-200 Hz.2.The noise of the ground road is relatively high,and the monitor results of the two roads0.2m away from the road boundary are both larger than 70 d B(A).The spectral characteristics of the two roads are similar,and the main contribution frequency band is 800-2000 Hz.3.The test points on each floor of the sensitive building basically do not meet the daytime and nighttime noise limit requirements of the 4a acoustic environment functional area.The vertical distribution of noise in sensitive buildings generally shows a law of the noise increasing to the highest then decreasing from the building’s bottom to the top.4.Tram and railway noise is masked by road noise and contributes little to sensitive buildings.The noise of the subway increases the average noise of sensitive building test points in daytime by more than 3d B(A),and the average noise increase at nighttime by more than4 d B(A).5.The overall noise spectrum of sensitive buildings reaches a peak in the 630-2000 Hz frequency band,with 1000 Hz being the highest,which is a typical road traffic noise contribution frequency band.When the subway appeared,the noise spectrum increased in the lower frequency range of 50-1000 Hz.6.Cadna/A software was used to establish a noise model in this area,and after correction,the simulation obtained the order of the noise contribution value of each sound source in this area to the sensitive building as tunnel road section﹥subway﹥tram parallel road section﹥railway﹥tram.7.Through the established model simulation and actual measurement of noise reduction effects,designed a set of comprehensive noise reduction engineering measures,they are combined noise reduction measures for subway fully enclosed sound barriers,3.5m high curved top sound barrier of the road tunnel underneath,and integrated OGFC drainage asphalt pavement to reduce environmental noise outside sensitive buildings,and sound insulation windows to reduce indoor noise.The noise reduction effect is good,and it provides a certain reference basis for the noise control of the multi-mode complex traffic environment. |
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