大洪岭2号隧道内（长隧道）密级配路面、单层排水降噪路面及双层排水降噪路

大洪岭2号隧道内（长隧道）密级配路面、单层排水降噪路面及双层排水降噪路面噪声纵向衰减规律进行测试，得到隧道内三种类型路面工况的噪声衰减特征规律，沿隧道纵向声压级值大小进行线性拟合，得出沿纵向的衰减率。纵向分布曲线如图4.8所示，通过线性拟合(y= a*x+b)后得出的隧道不同路面的纵向衰减率。<br><br>通过试验测试，得到隧道不同路面的纵向衰减率如图4.7所示，三种路面衰减率有显著的差异，密级配路面的纵向衰减率为0.076dB/m，单层排水降噪路面的纵向衰减率为0.100dB/m，双层排水降噪路面的纵向衰减率为0.1316dB/m。得到在同一隧道环境内，密级配路面的噪声纵向衰减率最小，双层排水降噪路面的噪声纵向衰减率最大，单层排水降噪路面的噪声纵向衰减率居中。因此，采用排水降噪路面能够有效提高噪声的纵向衰减率，以降低隧道噪声和改善隧道声环境。

The longitudinal attenuation characteristics of noise on dense graded pavement, single layer drainage noise reduction pavement, and double layer drainage noise reduction pavement in Dahongling Tunnel 2 (long tunnel) were tested to obtain the noise attenuation characteristics of three types of pavement conditions in the tunnel. Linear fitting was performed along the longitudinal sound pressure level value of the tunnel to obtain the attenuation rate along the longitudinal direction. The longitudinal distribution curve is shown in Figure 4.8, and the longitudinal attenuation rates of different road surfaces in the tunnel are obtained through linear fitting (y=a * x+b).<br>Through experimental testing, the longitudinal attenuation rates of different road surfaces in the tunnel are shown in Figure 4.7. There are significant differences in the attenuation rates of the three types of road surfaces. The longitudinal attenuation rate of the dense graded road surface is 0.076dB/m, the longitudinal attenuation rate of the single-layer drainage noise reduction road surface is 0.100dB/m, and the longitudinal attenuation rate of the double-layer drainage noise reduction road surface is 0.1316dB/m. Within the same tunnel environment, the longitudinal attenuation rate of noise on densely graded pavement is the smallest, the longitudinal attenuation rate of noise on double-layer drainage noise reduction pavement is the largest, and the longitudinal attenuation rate of noise on single-layer drainage noise reduction pavement is in the middle. Therefore, using drainage noise reduction pavement can effectively improve the longitudinal attenuation rate of noise, reduce tunnel noise and improve the tunnel acoustic environment.

In Dahongling No.2 tunnel (long tunnel), the longitudinal attenuation law of noise of dense graded pavement, single-layer drainage noise-reducing pavement and double-layer drainage noise-reducing pavement was tested, and the noise attenuation characteristics of three types of pavement in the tunnel were obtained. The longitudinal attenuation rate was obtained by linear fitting along the longitudinal sound pressure level of the tunnel. The longitudinal distribution curve is shown in Figure 4.8, and the longitudinal attenuation rate of different road surfaces of the tunnel is obtained by linear fitting (y= a*x+b).<br> <br> Through the test, it is found that the longitudinal attenuation rates of different pavements in the tunnel are as shown in Figure 4.7, and there are significant differences among the three pavements. The longitudinal attenuation rate of dense graded pavement is 0.076dB/m, that of single-layer drainage noise-reducing pavement is 0.100dB/m, and that of double-layer drainage noise-reducing pavement is 0.1316 dB/m.. It is concluded that in the same tunnel environment, the longitudinal attenuation rate of noise of dense graded pavement is the smallest, that of double-layer drainage and noise reduction pavement is the largest, and that of single-layer drainage and noise reduction pavement is in the middle. Therefore, the drainage noise reduction pavement can effectively improve the longitudinal attenuation rate of noise, so as to reduce tunnel noise and improve tunnel acoustic environment.