Field measurement and numerical simulation were performed on the distortion of the compression wave generated by train entry and propagating through a slab track Shinkansen tunnel, which is the longest mountain tunnel in the world at present. The pressure of the compression wave measured at 12 locations. In the numerical simulation, the distortion of the compression waveform was calculated by one-dimensional compressible flow analysis which takes account of steady and unsteady friction combined with acoustic analysis on the effect of side branches. The results of numerical simulation agree well with those of the field measurement. Furthermore, the results show that the compression wavefront steepens in the early stage and smoothes down in the later stage of propagation.
