| 摘要 |
PURPOSE: To gradually increase or decrease the excavating diameter while excavating, by widening a part or the outer shell plate constituting the shell from the inside of an excavating machine and closing the peripheral clearances with the expanded plate and flange. CONSTITUTION: The ground around an excavating machine 1 is cut expansively by an overcutter 16 which can be extended by a specified length from the outer peripheral face of the cutter head 11. A part of a plurality of the outer shell plates 22A constituting the shell is widened from the inside of excavating machine 1. Subsequently, the clearance between the outer shell plates 22A brought by the expanding motion and the clearance brought at the peripheral part of the bulkhead 20 are closed while the tunnel is expanded. The clearance between the outer shell plates 22A is narrowed to contract the tunnel or excavate the tunnel constituting continuously changing tunnel diameters. |
