CONSTRUCTION METHOD OF UNDERWATER TUNNEL

PROBLEM TO BE SOLVED: To provide a construction method of an underwater tunnel capable of rationalizing a structural form of an approach, shortening a construction period and reducing a construction cost even in the case of the great depth of the water or the soft underwater ground. SOLUTION: The construction method of the underwater tunnel of the approach for connecting a water structure section to the underwater tunnel is constituted of a process for setting leg type underwater structures 2 on the underwater ground G in a predetermined area of the approach at a regular interval, an immersion process immersed on the leg type underwater structures 2 by towing a box body 3 constituting the underwater tunnel in a floating state, a fixing process moving the box body 3 to a predetermined position at need, connecting it with the neighboring structure, at the same time, fixing on the leg type underwater structures 2, and the immersion process and the fixing process are repeated over a predetermined section to construct the underwater tunnel.