Investigation On Effect Factors Of Tire/Road Noise And Evaluation Of Sound Quality For Compact Asphalt Pavement

According to previous studies, the factors that affect the noise of the tire/road mainly included tire vibration and air pumping function, but for compact asphalt pavement, which effect were more significant and the factors that affect these two functions were still lack of research. In this paper, the tire/road noise was studied as the research object, the effect factors of tire/road noise were analyzed and ways to reduce the tire/road noise were put forward, and the sound quality of tire/road noise was evaluated, specific studies were as follows.Firstly, the typical compact asphalt pavements in Beijing were selected to collect noise with method of Close-proximity Sound Intensity, which included rubber asphalt pavement, AC pavement, SMA pavement, SMC pavement(a modified asphalt pavement with rubber extract), and basic law of sound pressure level and frequency spectrum were studied, to provide support for the next studies on reducing the sound pressure level of the tire/road noise and evaluation of the sound quality based on frequency spectrum.Secondly, controlling variable method was adopted to study the tire vibration, in the case of other factors remain unchanged, significant correlation between sound pressure level of tire/road noise and tire vibration was found, the greater the tire vibration, the greater the sound pressure level of the tire/road noise. Then, the factors affecting the tire vibration were studied, the texture depth was found to affect the random vibration of the tire in the vicinity of the equilibrium point, pavement smoothness and road damage condition were found to affect the peak of tire vibration. In the end, ways of keeping good smoothness, reducing texture depth and dynamic modulus, keeping good road condition were put forward to reduce tire/road noise.Then, air pumping function as another influence factor of the tire/road noise was studied, and the sound absorption coefficient as the evaluation index of the air pumping function of the compact asphalt pavement was put forward, the correlation analysis of tire/road noise under the effect of vibration and sound absorption coefficient was made, and it was found that sound absorption coefficient had greater influence on the tire/road noise than the tire vibration. By the experiment of sound absorption coefficient, the influence of thickness, gradation, asphalt type and test surface type on sound absorption coefficient was explored, and the effect of thickness and test surface type on sound absorption coefficient was the most significant. Then a test to improve the sound absorption coefficient by modifying the surface of Marshall test piece was designed. The sound absorption coefficient was found enhanced because Helmholtz sound absorption structure was formed after slow release snow-melting agent melted.Finally, the sound quality of tire/road noise quality was evaluated, and the evaluation parameters included sharpness, harshness, fluctuation and loudness, by contrast with white noise and pink noise, it was found that sharpness was not the cause of the deterioration of sound quality of the tire/road noise. Focus on the tire/road noise loudness was studied, according to the calculation principle of Zwicker sound level, loudness in critical band 1~8Bark, especially 1 Bark, had the greatest influence on loudness, then compared the tire/road noise loudness with pink noise and white noise, finally, ways of reducing the noise sound pressure level and widen frequency domain where tire/road noise peak was were proposed.