Abstract
The magnitude of an impulsive pressure wave (micro-pressure wave) emitted from a tunnel portal is approximately proportional to the pressure gradient of a compression wave at the tunnel exit portal. It is confirmed that ballast layers installed in a slab-track tunnel have effect on the reduction of the micro-pressure wave by a field measurement. In this study, method of a numerical simulation is investigated for estimating the effect of the ballast layers on the reduction of the micro-pressure wave. The results indicates that the effect of the ballast layers can be simulate by calibrating a parameter of a unsteady friction term.
