A pressure wave radiated from a tunnel entrance when a train enters a tunnel

摘要

It is well known that when a compression wave generated by a high-speed train entering a tunnel propagates through the tunnel and arrives at the distant exit, a micro-pressure wave is radiated from the exit portal toward the surrounding area. In addition, several pressure waves are radiated toward the outside area from the entrance when a train enters the tunnel and from the exit when the train leaves it. We call the former a tunnel entry wave, and the latter a tunnel exit wave. Although the tunnel entry/exit wave is usually weaker than the micro-pressure wave, they could cause an environmental problem with increases in the train speed. In this study, model experiments and numerical analysis are performed to investigate the fundamental characteristics of the tunnel entry wave. Based on the results, a simple acoustic model of the tunnel entry/exit wave is presented.