Research On Sound Absorption And Design Of Noise Barrier Of Recycled Tire Composite Type

Noise barrier is an economical and effective method of mitigating noise impaction that is common use in the expressway. In order to take balance between on the technology of noise barrier,expense and environment, a new type of noise barrier shall be designed to be effective on mitigating noise impaction, firm in use, be harmonious with local landscape.This dissertation introduces and discusses the basic theory of reducing noise in the expressway, the material impact on the performance of noise reduction, and the defect of domestic noise barrier. It also gives the character of material suitable for the traffic noise barrier. Starting with the structure of the composite type noise barrier, the mechanism of noise absorption of spongy material and perforation board, the impact of vibration of perforation board and the reason why the noise absorption of sound barrier of recycled tire composite type is eminent in the middle and low frequency have been discussed.By using the dynamic signal collector, a frequency analytical experiment has been done, in which formant frequency has been detected. After large numbers of repeating experiments, the resonance frequency has been detected, and the mechanism of noise absorption has also been analyzed.This dissertation discusses principal and measuring method of reverberation -chamber which can measure the absorption coefficients of tyre composite noise barrier and perforated–panel and fiberglass noise barrier. After that, the test results are analyzed and compared to validate the new type of noise barrier.Several calculation examples are given, combining with the noise barrier project application in expressway. It is suggested that the absorption coefficient of noise barrier in expressway should be eminent in the middle and low frequency in order to make great contribution to whole sound absorption. If not, the reverberation barrier should be used in expressway, which can reduce the price of project, as well as keeping the eminent performance of noise reduction.