| 摘要 |
PURPOSE:To form a ring-shaped lining along the periphery of a planned tunnel in the ground in advance when the tunnel with a large diameter is constructed. CONSTITUTION:A ring-shaped rotary cutter head 5 is provided to the front end of a shield body 1 consisting of inner and outer double cylindrical frames 1a and 1b, a ring-shaped space is excavated by the ring-shaped cutter head 5 and, at the same time, concrete filled in the ring-shaped space by a front and rear slidable press ring 13 provided to the inside of the rear end of the shield body 1 is compacted to form a ring-shaped lining. In addition, a small dia--meter tunnel is excavated by a small diameter circular cutter 20 provided to the front end of a small diameter shield body 21 mounted to a proper position of the circumference of the inner cylindrical frame 1b of the shield body 1 as a unit. The small diameter tunnel is used for a piping passage of a concrete- conveying pipe, etc., and a sediment discharging passage. |
