隧道噪声传播扩散规律及其检测方案探讨

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。

Discussion on Propagation Rules and Detection Schemes of Noise in Tunnels

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 dB, 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 dB of noise in tunnel is largest in the middle and smallest at the ends; and the dB 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 cross section; 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.