Abstract
Field measurement and numerical simulation are performed on the distortion of a compression wave propagating through a slab-track tunnel longer than 20 km, which is the longest on the ground in the world. The compression wave which is generated by a train entering the tunnel is measured with 12 pressure transducers set along the wall inside the tunnel. In the numerical simulation, the distortion of the compression waveform is calculated by one-dimensional compressible flow analysis combined with acoustic analysis on the effect of side branches. The results show that the compression wavefront steepens in the early stage but smoothes down in the later stage of propagation.
