Abstract
The phenomenon in which tsunami flows backwards and carries out the overflow stream of the drainage canal to land is observed. In the case of the case where a vertical shaft is blockaded with a lid as a measure which prevents an overflow stream, the pump inlet channel of a plant institution, it is thought that it has an effect of the gaseous phase in pipe internal pressure or the amount of overflow streams. In this study, the hydraulic model experiment for the tsunami which serves as gas-liquid two-phase flow in an underground pipeline was carried out, measurement which paid its attention especially to pipe internal pressure was performed, and it was examined what kind of influence the gaseous phase would have. As a result, existence of the gaseous phase had influenced greatly the phenomenon which arises in an underground pipeline, and it became clear also to pressure fluctuation to do a big change.
