Characteristics of the Pressure Wave Radiated from an Entrance Portal When a Train Enters a Tunnel

Abstract

A high-speed train entering a tunnel generates compression and expansion waves inside the tunnel, which are propagated through the tunnel. In addition, the entering train generates negative and positive impulsive waves outside the tunnel, which are radiated directly from the entrance portal to the surroundings (tunnel entry wave). Experiments have been conducted on the tunnel entry wave by using a scale model of simple geometry under the conditions that the maximum entry speed is over 400 km/h. The experimental results are compared with the theoretical results obtained by Howe and are found to be in good agreement in regard to the waveform, speed dependency and directivity.