绿化林带对交通噪声的衰减效果

The effects of traffic noise attenuation by green belts

为了研究公路绿化林带的降噪效果,对路侧林带降低实时交通噪声的效果进行定位测量,并将交通噪声人工编辑为不同频率的噪声,在远离交通噪音的林带中进行模拟试验,测定林带对不同频率噪声的衰减效果.结果表明:林带对交通噪声衰减有一定作用,其作用随能见度增大而降低;林带降噪效果随林带宽度增大而增大,可决系数为0.990,但在30m宽度内随林带宽度的增加,噪声的降低速率有所下降;不同林带类型的降噪效果有所不同,所选30m宽林带类型中,国槐纯林的降噪效果最佳可达15.38dB,而杨树、柳树纯林降噪效果较弱,分别为7.25、11.02dB;林带对中低频率噪声的平均衰减作用高于高频率噪声.

After on-site investigation of traffic noise attenuation by green belts, the noise recordings were redacted by a computer according to different signal frequencies and this redacted signal was tested in green belts far away from traffic noise to simulate the effects of noise attenuation by green belts. The results showed that ① green belts can reduce traffic noise to some extent, but its effects diminish as visibility increases, ② the effects of noise attenuation increase with the width of the green belts （ the coefficient of determination is 0. 990） however the noise attenuation rate declines with belt width increases beyond 30 m,③ the effect of noise attenuation is different for different green belt types. The maximal noise attenuation by Robinia pseudoacacia is 15.38 dB when the width is 30m,but 7.25 and 11.02 dB by Populous and Salix species,respectively,and ④ the effects of noise attenuation by green belt are different for different noise frequencies. Attenuation is better for low-middle frequency than for high frequency noise.