Research Progress on Sound Field Distribution Characteristics and Noise Reduction Technology in Highway Tunnels

In response to the problem of noise control in highway tunnels, the system has carried out research on noise source identification, propagation law analysis, and noise reduction technology review. Firstly, it is clarified that the main noise source in the tunnel is traffic flow, and the secondary noise source is existing equipment such as fans; In depth analysis was conducted on the distribution and propagation mechanism of noise pressure in the longitudinal and transverse directions of tunnels, revealing the characteristics of noise inside tunnels, and specifically pointing out the "sound focusing" and "reverberation" phenomena that exist in horseshoe shaped cross-section tunnels. Secondly, the noise reduction mechanisms, applicable scenarios, advantages and disadvantages of the current mainstream active and passive noise reduction technologies were comprehensively summarized. It was pointed out that passive noise reduction has a significant effect on mid to high frequency noise, while active noise reduction has more advantages in low-frequency noise control. Research has shown that effective control of tunnel noise in the future requires comprehensive consideration of factors such as road grade, traffic characteristics, and cross-sectional form, and the scientific integration of active and passive noise reduction technologies. This research result can provide important theoretical basis and technical reference for the theoretical research and noise reduction engineering design of highway tunnel noise control.