Abstract
A tunnel entrance hood decreases the pressure gradient of compression wave generated by a high-speed train entering the tunnel, and thereby, reduces the "micro-pressure wave" radiated from the distant portal. While the effect of the entrance hood has been marked, it becomes necessary to extend its length with costly works, in order to raise the entrance speed of trains. Therefore, we have been developing a new type of tunnel entrance hood equipped with pipes on its roof, which could decrease the pressure gradient of the compression wave with smaller hood length than conventional entrance hoods. We performed model experiment to investigate the function of pipes for controlling the pressure gradient waveform and reduction effect of the maximum pressure gradient. As a result, it is shown that the pipes equipped on an entrance hood could delay increase of the pressure and decrease the pressure gradient further.
