Evaluation And Optimization On The Sound Absorption Of Porous Asphalt Pavement

With the expansion of urban scales,rapid development of urbanization and motorization,the urban road traffic noise problems are getting more serious.Testing results of road traffic noise in 325 cities in China show that:proportion of cities plagued by noise pollution has reached 86.4%,in which the proportion of cities under intermediate and severe noise pollution reaches 22.1%.The traffic noise has become a social problem from a purely environmental issue.Some past research achievements of reduce the asphalt pavement noise have been applied in actual engineering,The current research of porous asphalt pavement performance focuses on drainage ability and material property,which is lack of study for noise reduction properties.The producing mechanism of tire/road noise and noise reduction principle of porous asphalt pavement have not been thoroughly researched.And the internal relations between microstructure characteristics and acoustic properties of asphalt pavement are also lack of theoretical research.This article discusses the sources of road traffic noise,analyzes the proportion of various noise sources and confirms the tire/road noise is the main road traffic noise.Also studies the mechanisms and influencing factors of tire/road noise,puts forward a method reducing the tire/road noise from pavement structure.Based on the acoustic characteristics of porous pavement materials,the two control methods of noise were analyzed:damage the sources of tire/road noise and manage the transmission routes.On this basis,the influence factors of sound absorption properties of porous asphalt mixture were studied by using stationary wave method,the results indicate that:the sound absorption performance decreases with the increase of air flow resistance;the peak absorption coefficient of porous asphalt mixture increases with the increase of porosity and the peaks are concentrated in the frequency range from 900 to 1000,the peak moves to high frequency as the porosity increase;it is better to use smaller nominal maximum aggregate size to reduce the noise level;with the pavement thickness increases,the average absorption coefficient of porous pavement in the high frequency band will decreases.On the base of pore structure characteristics,the microstructure model of porous asphalt mixture was established by physical geometrical to analyze the influence of the pore structure characteristics on the acoustic performance of porous asphalt mixture.Using electro-acoustics principle to compare to the microstructure of porous asphalt mixture model,the relationship expression between acoustic parameters of porous asphalt mixture and the pore structure parameters was established.On that basis,the influence of each parameter on the acoustic performance of porous asphalt mixture was analyzed and reasonable value scope for each parameter was put forward.Based on microstructure of porous asphalt mixture,a finite element numerical model was established to research the structural parameters of asphalt pavement.Through the analysis of vibration characteristics on the road,the modal analysis of different aggregate structure was carried out using the finite element method.The sound absorption characteristics of asphalt pavement were studied from damping vibration.Then the topology optimization of structural parameters was carried out based on noise reduction performance of asphalt pavement.After the comparison with the existing tire noise test methods,the trailer method was choosed.Based on the interaction theory between tire and road noise,the near-field test trailer with two-wheeled which could simulate the actual operation conditions was developed by using multi-channel noise and vibration measurement analysis system for data collection and analysis.Noise conditions of different pavement structures were measured and the influence of different road conditions on the interaction between tire and road noise were discussed.The test results were compared with the model simulation results to verify the model validity.