Abstract
When a tunnel is submerged, the air is stayed in it. Here, the rock mass surfaces are exposed in the tunnel. The condition of water sealing for the staying compressed air is that, the pressure of the compressed air is smaller than the pressure of void water pressure in rock masses. By the results of measurements, it is ensured that the compressed air stays for ten months in the tunnel. Moreover, the change in terms of the time of void water pressure in rock masses have been cleared. Then the outline of the results for the field measurements will be described.
