Abstract
In HIDA pilot tunnel, the hydraulic head pressure which is equal to thickness of earth covering is confirmed by boring, as the rock pressure is increasing due to high earth covering which is 1000m. By using a double steel pipe, geology ahead of the tunnel face could be investigated more. Large-scale crash was avoidable with the AGF method of construction. The prior measure and construction situation, which were carried out by TBM in a lot of groundwater, are reported
