CONSTRUCTION METHOD FOR ENLARGING CROSS-SECTION OF TUNNEL, AND TUNNEL

摘要

PROBLEM TO BE SOLVED: To provide: a construction method for enlarging a cross-section of a tunnel, which makes working efficiency proper with a simple configuration and which is used to enlarge the cross-section while bringing an existing tunnel in service by a protector; and a tunnel.SOLUTION: A step of excavating a widened part-planned area by installing a protector for securing a passage space within an existing tunnel and advancing a construction trestle on which a construction machine is loaded in parallel with the protector, and a step of advancing the protector so that a leading part can be constantly positioned ahead of a cutting face formed by excavation are repeated.SELECTED DRAWING: Figure 3