An impulsive pressure wave which is called a "micro-pressure wave" or a "tunnel sonic boom" radiating from a tunnel exit is one of the important environmental problems in high-speed railways. The strength of the impulsive wave depends on the waveform of the compression wave at the tunnel exit. In this study, the distortion of the compression wave during its propagation through the tunnel is investigated by field measurement and numerical analysis. The field measurement is conducted in the concrete slab (ballastless) track tunnel of the Shinkansen. The numerical analysis is also carried out on one-dimensional compressible flow using upwind TVD scheme. It takes account of steady and unsteady wall friction and of heat transfer to the tunnel wall. Our original numerical analysis method is based on Galilei transformation of the coordinate system moving with the compression wave. The results show that the agreement of the numerical analysis and the field measurement is good.
