| 摘要 |
PROBLEM TO BE SOLVED: To provide a tunnel construction method capable of preventing collapse of a working face of a tunnel, and capable of preventing generation of dry quicksand of the working face of the tunnel, by forming the front natural ground of the working face of the tunnel as the natural ground of a water content condition suitable for excavation.SOLUTION: Before excavating a regular tunnel 1, a propulsive tunnel 2 aiming at draining is formed on a front natural ground 5 of a working face 4 of the regular tunnel 1, and while positioning a working face 6 of the propulsive tunnel 2 forward by a constant distance H more than the working face 4 of the regular tunnel 1, boring work of the regular tunnel 1 and boring work of the propulsive tunnel 2 are simultaneously executed. The constant distance H is set within a range of 2 m-5 m. A double pipe capable of realizing a sealed type propulsion method in a non-drainage structure state in propulsion and formable in a drainage structure state after finishing the propulsion, is also used as a pipe 3 for constituting an outer shell of the propulsive tunnel 2. |
