Study On The Highway Tunnel Noise Field Distribution Effected By The Fixed Point Source

With the rapid development of tunnel construction in China, the problems of traffic noise in the tunnel has attracted more and more attention. The prediction method of traffic noise in highway tunnel has been well developed at home and abroad. However there are few study on the distribution regular of the acoustic field in the tunnel. Tunnel width is usually more than10meters to tens of meters. Compared with the acoustic wavelength, the tunnel width can’t be ignored. So the research should adopt wave acoustics theory. For the long space semi enclosed sound field, sound field simulation of tunnel can be better within the FEM.The acoustic field of an actual tunnel affected by the symmetrical arrangement single point sound source is simulated by the Virtual. Lab software based on the FEM, and the distribution characteristics of the sound field is received based on the calculation results. Then the calculation models are established by use the FEM to calculate the field distribution under different conditions in the tunnel. On this basis, this paper discusses the change of the sound field distribution inside the tunnel when the sound source position, size of the tunnel section, tunnel wall sound absorption properties or the pavement material sound absorption property is changed.The results show that the acoustic FEM can reflect the fluctuation characteristics of acoustic field in the tunnel, and noise field distribution inside the tunnel can also be calculated correctly noise field distribution inside the tunnel. Under certain tunnel, the point sound source position has great effect on the distribution of sound field near the sound source, but it has little influence on the whole distribution of sound field in the tunnel. The tunnel section size has little influence on the distribution of sound field in the tunnel. The sound absorption characteristics of tunnel wall material and the sound absorption characteristics of the road surface material can affect the amplitude of the pressure in a certain extent, but had no effect on the acoustic field distribution inside the tunnel.