基于无限大障板圆形活塞辐射原理的隧道微压波计算方法

Numerical Investigation of Micro-pressure Waves Radiated from a Tunnel Exit Based on the Model of Radiating of Circular Piston in the Infinite Plat

高速列车驶入隧道端口瞬间在车头前形成压缩波。该压缩波沿隧道以声速向出口端处传播,并在洞外形成微压波。本文根据声学中无限大障板圆形活塞的辐射模型,开发了已知隧道出口端内压缩波压力梯度和大小时的微压波计算程序,并采用国外试验结果验证了程序的正确性。结合拟议的我国高速铁路隧道特征,初步分析了洞口微压波的主要影响因素,显示列车速度、隧道断面面积影响较大。微压波的大小与观测点有很大关系,这对于判断微压波的强弱、危害及其标准研究有很大关系。结果分析也说明所建程序的合理性与简便性,是一种适合工程设计方案比选的方法。

When a high-speed train enters a tunnel,a compression wave is generated in the front of the train. This pressure wave propagates to the tunnel exit and spouts as an impulsive wave which causes a blast sound. This impulsive wave is called the micro-pressure wave. The micro-pressure wave causes abrupt rattling of window frames or shutters of houses and raises a new environment problem. The main processes of determining the micro-pressure wave contain determining the compression wave in the tunnel import, the wavefront distortion of the compression wave along the tunnel and the pressure gradient of the compression wave in the tunnel exit. In this paper the solution method is developed for calculating the micro-pressure wave around out of the tunnel exit based on the model of acoustic radiation of the circular piston in the infinite plat. The micro-pressure wave strength is proportional to the pressure gradient of the compression wave out of the tunnel exit. The ground influence is considered in which the tunnel cross sectional area is treated as the semicircle of the area unchanging. The characteristics of the micro-pressure wave is investigated according to the proposed tunnel cross sectional area and high speed train nose of our country. The trainspeed and tunnel cross sectional area are the main influence factors of the micro-pressure wave as the tunnel length is not considered. The micro-pressure wave strength decreases with the distance from the measure point to the tunnel exit increasing. The analytical results show the consistent conclusion between the micro-pressure wave and its influencing factors comparing with foreign results, and it can be used to analyse the micro-pressure wave during the initial design of the high speed railway tunnel.