CONSTRUCTION METHOD OF BRANCH TUNNEL, AND SPECIAL RING WALL

摘要

PROBLEM TO BE SOLVED: To construct a branch tunnel from a main track tunnel without installing a vertical shaft from the ground or improving the ground. ;SOLUTION: After a special ring wall 7 of cylindrical shape with a branch start opening 11 is built up in a drum part 2 of a shield machine l, a propulsion machine for constructing a branch tunnel is carried into the special ring wall 7. After bringing the propulsion machine close to the inner peripheral surface of the drum part 2 of the shield machine 1, the shield machine is made excavate forward. The start opening 11 is thereby exposed to the natural ground. A cylindrical ring wall is then constructed at the rear end part while making the propulsion machine excavate forward. The branch tunnel is therefore constituted without installing a vertical shaft from the ground or improving the ground.;COPYRIGHT: (C)1998,JPO