| 摘要 |
PROBLEM TO BE SOLVED: To excavate including both end parts of an arched undercut ditch having a circular arc-shaped cross section in a flat cross-sectional tunnel having a large radius to the height. SOLUTION: In a tunneling machine 1, a cutter traversing device 4 has an undercut ditch excavating chain cutter 2 so as to be movable in the longitudinal direction, projects a circular arc-shaped guide member 3 having an intermediate part curving so as to be recessed to the tunnel outside, and is provided so as to be movable along a circular arc-shaped arch frame 5 oppositely arranged on a working face, and the arched undercut ditch 19 is excavated on the outer periphery of the working face by moving along the arch frame 5 via the cutter traversing device 4 while circularly moving the undercut ditch excavating chain cutter 2. The circular arc-shaped guide member 3 is turnably installed on the cutter traversing device 4. |
