| Summary: | While most studies evaluate sound-absorption performance of double-layer porous asphalt (DLPA) pavement using macroscopic approaches, this research conducts mesoscopic analysis through acoustic simulations. DLPA's acoustic behavior was examined by reconstructing its three-dimensional (3D) mesoscopic pore structure using an integrated approach. This approach combined X-ray CT scanning, discrete element method (DEM), and digital image processing. Three macroscopic parameters and three mesoscopic parameters were employed to characterize the DLPA's properties. Laboratory-validated finite element method (FEM) simulations assessed how these parameters individually and jointly affected sound-absorption performance of DLPA. The results revealed that lower-layer parameters exerted approximately twice the influence on sound absorption compared to upper-layer characteristics. Maximum noise attenuation of 27 % was attained by elevating mesoscopic and macroscopic characteristics in the lower layer (except thickness) while reducing equivalent upper-layer parameters. Notably, owing to Helmholtz resonance effects, DLPA with ''two-sieve-gap'' configurations (e.g., PA-10 +PA-20) demonstrated superior sound absorption performance compared to conventional ''one-sieve-gap'' designs (e.g., PA-13 +PA-20). Targeted optimization of all three mesoscopic parameters could achieve noise-reduction coefficients of 0.4, providing a scientific basis for designing high-performance DLPA pavements with exceptional acoustic properties.
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