| 摘要 |
PROBLEM TO BE SOLVED: To construct an overlaid layer with a constant thickness efficiently with pneumatically-applied concrete as timbering for wall surfaces, on wall surfaces immediately after excavation in a side ahead of a tunnel boring machine and eliminate various bad effects of pneumatically-applied concrete in a side behind the tunnel boring machine. SOLUTION: A large diameter tunnel of a constant length is excavated by an excavation blade 14 protruding in the front of a rotary cutter plate 3 and an excavation blade 17 protruding in the circumferential edge in the diametrical direction in an extensible manner by advancing the front body section 1, after the rear body 2 of a tunnel boring machine is supported on an already-constructed concrete overlaid layer C' through a rear gripper 6. And then, after the front body section 1 is retreated, with a spray nozzle 7 protruded from the opening 20 of the cutter plate 3, the thick concrete overlaid layer C is sprayed to the excavated wall surface T of a tunnel. And then, by advancing the front body section 1 while adjusting the length of protrusion of the excavation blade 17 provided in the circumferential edge of the cutter plate 3 and turning the cutter plate 3, the concrete overlaid layer C is reshaped to a concrete covered layer C' with a constant thickness that is a flat in the inside perimeter, by the excavation blade 17. |
