| 摘要 |
PROBLEM TO BE SOLVED: To provide a tunnel excavating method which ensures a sufficient earth infiltration preventing function or cutoff performance even under an environment where earth pressure or hydraulic pressure becomes high, and facilitates construction of a standard tunnel and a widened tunnel, to thereby shorten a construction period and cut construction cost. SOLUTION: There is provided a shield machine 1 which includes a cutter 2 for driving a standard shaft and a widened spread shaft, a skin plate 5 arranged outside a shield main body 3, and a spreading member 6 protrudable from the skin plate 5 in a widened direction. The tunnel constructing method is carried out by driving the standard shaft and the widened shaft by using the shield machine 1, and sequentially mounting standard shaft segments and widened shaft segments on an internal surface of the skin plate 5 or the widened member 6, to thereby construct both the standard tunnel and the widened tunnel. The shield machine 1 is comprised of a boundary member 20 for blocking a gap between the skin plate 5 or the widened member 6 and the standard shaft segments at the time of starting construction of the widened tunnel, and connecting lining members together. |
