Research On The Effect Of Trunk Road Noise On The Nearby Campus And The Design Of Sound Barrier

With the urban road construction and development of transportation, traffic noise pollution has become increasingly serious, the community and people's universal attention to it, and actively looking for the effective measures to reduce traffic noise and other mobile sources. Sound barrier is an effective and economical way to reduce traffic noise. The research on sound barrier noise reduction technology, are of great significance to improve the quality of people's living environment and the sustainable development of urban construction. Through the analysis on research methods, research results, research progress and the status quo of the sound barrier on the current inside and outside, we can found that the application of sound barriers are mostly concentrated in the light rail, rail, elevated and high-speed roads, less in the main road of city. Many survey data show that noise in the school which adjacent to Route traffic was significantly higher than that in other schools, the main noise pollution in campus is traffic noise. Schools, residential areas and office buildings which on the side of the city road, all belonging to noise-sensitive point, so design study on sound barriers is very important.This paper in accordance with the sound barrier insertion loss given in the design specifications, and other relevant terms of definition, analysis and research the principles of sound barriers and noise-reducing effects of noise assessment of the indicators. The results showed that: the mechanism of noise-reducing is introduction of sound barrier between the noise sources and receiving, the sound waves reached the reception must be through the diffraction, which will lengthen the sound transmission path, resulting in the reduction of noise, that is, when the sound waves issued by noise source encountered the sound barriers, it will spread along three paths, part of the waves reached the reception by diffract across the top of the sound barrier, part penetrating the sound barrier reached the reception, part reflecting on the sound barrier wall. Sound barrier insertion loss mainly depends on the spread of sound distribution that sent along the path of the sound waves. Sound waves radiated by source form a "sound shadow section" behind the barrier, the size of the section depends on the sound barrier effective high H, the location between the sound source and sound, and the frequency of sound waves. Second, the effect of the sound barrier can be expressed by the insertion loss generally, it bear on the frequency of noise, the high of barriers and the distance between the sound source and receiving points and so on.In allusion to different source (point source, unlimited long-term source, limited long-term source), analyzed the characteristic of source and the principles of sound barrier, then educed the theoretical calculation formula of sound barrier insertion loss. According to the amendment to the limited road which does not consider the parameters of the ground section in the FHWA road traffic noise the forecasting model, derived the theoretical calculation formula of infinite source and limited sound barriers insertion loss.According to the model of the sound barrier insertion loss established in this text, mainly from the acoustic point of view analyze and explore the methods of geometric design to the sound barrier in city road, including the reasonable geometric position to setting up the sound barrier, through analysis the sound field of sound barrier's both ends to confirm the effective length of the sound barrier, and so on. The dissemination of distance is the determining factors to affect the acoustic attenuation, ascertained the sound barrier's height through analyzing the sound path difference of the dissemination of the noise source, and received the calculating formula for the thickness in accordance with the established thickness principles of sound barrier. In addition, the paper also analyzed the shape of modern sound barrier, the structure characteristic, the reduction mechanism of components which is the composition of sound barrier and its impact, discussed and studied the design steps, methods and points of sound barrier, such as the sound barrier acoustic design, shape design, structural design, landscape design, the design of acoustic components, bring forward an way pursuit the visual effects at the same time meet the design objectives, provides a basis for the sound barrier design.At present, Most of the noise studying is concentrate in the environmental noise pollution evaluation of residential areas in urban, involves a little noise investigation of campus. To further verify the noise reduction effects of sound barrier, this article has been selected the NO.8 middle school of Changchun which adjacent to the Yatai Street to study, measured its noise on the spot, according to earlier studies of acoustic design principles and methods, designed the sound barrier accordingly, then on the basis of the Method of limited and the basic principles of BEM, using the SYSNOISE which is the boundary element analysis software to simulate the sound barrier, gained the sound field and the scene acoustic capability of the sound barrier; and verified the reliability, accuracy of the method of software simulation. The results show that the sound barrier which was designed has a good acoustic reduction effects. Using the simulation software to predict the effects of sound barrier on computer provides a new way to the design and verification of sound barrier.