TUNNEL

PROBLEM TO BE SOLVED: To solve the problem of being economically disadvantageous in forming a concrete wall forming a tunnel inner wall in a tunnel body as a structure having strength endurable against ground water pressure, since the thickness of a water cut-off layer formed by a ground improvement by chemical injection must be thickened and chemicals such as water glass used for forming the water cut-off layer are also dissolved in underground water with the lapse of time, when checking the inflow of the underground water into a tunnel hole, in a conventional tunnel. SOLUTION: This tunnel has a water impermeable layer 3 having a coefficient of permeability lower than that of the original ground and permanently maintaining the function of allowing the passing of water, on the outer periphery of the tunnel hole 2, and has the concrete wall 7 of a structure having no dynamic resistance function to the ground water pressure on the inner surface 4 of the tunnel hole 2. COPYRIGHT: (C)2007,JPO&INPIT