公路隧道噪音傳播

Noise Propogation in Road Tunnels

劉德源(Der-Yuan Liou) ； 洪宏基(Hong-Ki Hong)

《中華民國振動與噪音工程學會論文集》 1994 (1994/06) Pp. 91-100

https://doi.org/10.30028/CSSVANNUAL.199406.0091

摘要

本文理論方面以三維聲波方程式解析隧道噪音傳播特性。考慮的隧道剖面有圓平底、橢圓平底及三圓弧平底（如圖l）三種。將二維霍姆荷茲方程式表示在雙極座標系統上，求其特徵函數即可得圓平底剖面的可傳播模態及消失模態。進而經適當的映像轉換即可得橢圓平底剖面的模態。利用等值徑向與平底尺度最小平方誤差的觀念，則三圓弧平底剖面可以橢圓平底近似，文中即以懷恩隧道為例，先近似橢圓平底，再求其傳播特性。
實測方面，以機車與轎車做爲噪音源，利用聲強技術測算聲功率。至懷恩隧道作多點現場量測，變化車速，做聲壓歷時量測分析，由一系列的量測數據來探討隧道的聲場特性，同時對現場量測的技術與困難也做較深入的說明，以供參考。

並列摘要

This paper utilizes the three dimensional acoustic wave equation to investigate the propagation characteristics of road tunnels. There are three kinds of shapes of the cross sections of the tunnels considered herein. truncated circles, truncated ellipses, and three circular arcs with straight base. To derive the propagation modes and evanescent modes of the tunnels of the abovementioned shapes, we solve for the eigenfunctions of the two dimensional Helmholtz equation expressed in the bipolar and bielliptic coordinate systems, the latter of which is established from the former by a series of snapping transformations. The shape of Hoai-un tunnel located in the southern suburban Taipei which is of the shape of three circular arcs with straight base is approximated by the truncated ellipse by minimizing the mean square of the differences of the radial dimensions of Hoai-un and the truncated ellipse. Thus the sound propagation characteristics of Hoai-un tunnel can be determined.
To investigate the sound Propagation characteristics of Hoai-un tunnel on site, we drove in several speeds a car and a motorcycle, the sound power levels of which were calculated in advance from sound intensity mea surements, and measured, the sound pressure levels at a series of points along the tunnel. Based on the data collected and the experiences gained, the sound propagation characteristics are discussed arid the in-situ measuring techniques and the difficulties involved are explained.