隧道噪声传播扩散规律及其检测方案探讨

Discussion on Propagation Rules and Detection Schemes of Noise in Tunnels

隧道噪声是影响行车环境和安全的重要因素,掌握其传播扩散规律是开展噪声控制的前提和依据。通过理论与实测相结合的方法对隧道噪声大小、分布规律、混响时间及频谱特性进行研究,并对隧道检测方案进行探讨。研究结果表明:1)隧道噪声大小在空间分布具有一定的规律性,沿纵向呈中间高两端低的分布规律,且在隧道进口前50 m增加迅速;2)隧道横断面内的直达声是噪声的主要来源,一次反射声在其声聚焦处对噪声影响巨大,而混响声则恶化了隧道内的整体噪声情况;3)隧道内噪声主要是中低频噪声且呈现明显的双峰状,低频和中频峰值分别出现在100 Hz和1 200 Hz附近;4)隧道混响时间与隧道断面形状、边界平均吸声系数以及噪声频率有关,周长面积比越大、吸声系数越大以及噪声频率越高都会使得混响时间变小;5)隧道噪声检测参数应包含A计权声压、噪声频谱特性和混响时间,具体测点布置应综合考虑隧道长度和横断面形式,并结合当前技术手段科学制定。

The noise in tunnel affects the driving environment and safety much; as a result,it is very important to study the propagation rules and detection schemes of it. The d B,distribution rules,reverberation time and frequency spectrum characteristics of the noise in tunnel are studied by theoretical calculation and site monitoring; and then the noise detection schemes are discussed. Some conclusions are drawn as follows： 1） The longitudinal distribution rule of d B of noise in tunnel is largest in the middle and smallest at the ends; and the d B of noise in tunnel increases a lot far away tunnel entrance of 50 m. 2） The direct sound is the main source of noise in tunnel within tunnel horizontal crosssection; the first reflected sound has a great influence on noise in tunnel at the focusing point of sound; the acoustic environment in tunnel is worsened by reverberant sound. 3） The main noises in tunnel are medium and low frequency noises and show clear bimodal shapes; the peak values of low frequency noise and medium frequency noise are 100 Hz and 1 200 Hz respectively. 4） The reverberation time in tunnel is related to shape of tunnel cross-section,average sound absorption coefficient of tunnel boundary and noise frequency. The reverberation time decreases with the perimeter-area ratio of tunnel cross-section,sound absorption coefficient of tunnel boundary and noise frequency increase. 5） The A-weighted sound pressure,frequency spectrum characteristics of noise and reverberation time should be included by the detection parameters of noise in tunnel; the tunnel length,shape of tunnel cross-section and technical level should be considered when make arrangement of noise monitoring points.