Abstract: To investigate the effect of pores in porous asphalt mixtures on noise absorption, the three-dimensional (3D) connected pores of OGFC-13 with different porosity were reconstructed and separated by use of XCT scanning porous asphalt mixture specimens. The shape characteristics of connected pores, such as curvature, length, inner wall roughness, cross-sectional area, and ellipticity were analyzed. The finite element software was used to simulate the sound transmission in a standing wave tube, and the sound absorption coefficients of porous asphalt mixtures under different sound frequencies were obtained. The relationship between the pore shape characteristics of the mixture and the sound absorption coefficients at high, medium, and low frequencies was analyzed. The results show that although the curvature of the connected pores in OGFC-13 ranges from 0.25 to 0.35 mm-1, the three-dimensional connected pores are extremely abundant, with a length of connected pore over 980 mm in a 3 cm cube. The ellipticity of nearly 30% of the pore cross-section is around 0.9, and the roughness of the inner wall of the connected pores is extremely uneven, showing a clear bimodal distribution. There is a certain linear relationship between the cross-sectional size of the pores, the roughness of the inner wall, and the sound absorption coefficient in the high-frequency range (2000~3000 Hz). The larger the pore size, the rougher the inner wall, and the stronger the sound absorption ability of the mixture to high-frequency sound waves.

Key words: highway engineering; sound transmission; sound absorption coefficient; porous asphalt mixture; finite element method; connected pore

摘要： 为分析多孔沥青混合料孔隙对噪声吸收效果的影响，利用XCT扫描了多孔沥青混合料试件，重构并分离了不同空隙率OGFC-13三维连通孔隙，分析了连通孔隙曲率、长度、内壁粗糙度、横截面面积、椭圆率等形状特征；运用有限元软件模拟了声波在驻波管内的传播，得到了不同声波频率下多孔沥青混合料的吸声系数；分析了混合料孔隙形状特征与高、中、低频吸声系数之间的关系。结果表明：尽管OGFC-13内连通孔隙曲率在0.25~0.35 mm-1，但三维连通孔隙极其丰富，边长3 cm立方体内连通孔隙长度在980 mm以上；近30%孔隙横断面的椭圆率在0.9左右，且连通孔隙内壁粗糙度极不均匀，呈明显的“双峰”分布；孔隙横截面大小、内壁粗糙度与高频段（2 000~3 000 Hz）吸声系数具有一定的线性关系，孔隙越大内壁越粗糙，混合料对高频声波的吸声能力越强。

关键词: 道路工程；声传播；吸声系数；多孔沥青混合料；有限元法；连通孔隙