Patent ID: 7530765

Claim:
A method for constructing an intermediate wall, having an upper fixing type structure, of a three arch excavated tunnel, in which lining concrete is cast and fixed to an upper side of the intermediate wall, a lower portion of the intermediate wall has a small thickness reduced as much as the thickness of the lining concrete, and the lower portion of the intermediate wall is one type selected from the group consisting of a column type, an arch type and an intermediate wall type, the intermediate wall having the upper fixing type structure being one selected from the group consisting of a cast-in-place type intermediate wall, a steel plate girder type intermediate wall and a precast concrete type intermediate wall, the steel plate girder type or the precast concrete type intermediate wall has a drainage system in which a portion of the intermediate wall extending into a central tunnel of the three arch excavated tunnel is filled with a grouting agent without application of a waterproofing step, and an upper portion of the intermediate wall is drained such that water is induced toward side walls of the intermediate wall using a drain board and a waterproof layer and then sequentially flows toward the inside of the intermediate wall along a collection tank stopper, a collection tank and drain pipes.