| 摘要 |
PURPOSE:To prevent secondary crushing and tertiary crushing, stably support a foundation pile, improve excavation efficiency, and reduce the running cost. CONSTITUTION:A pipe 20 and a cutter head 4 on the drill pipe side are rotated by a rotary table and the like on the ground, and the natural ground is excavated with a cutter bit 1. The motor 18 of each muck moving device 17 is started, its rotation is transmitted to a screw blade 19 to rotate the screw blade 19, a water current toward the inside of the radial direction is generated between the cutter head 4 and the cutting edge, and the movement of the excavated muck 3 toward a center section (suction pipe 2) is assisted. The screw blade 19 of the muck moving device 17 moves the excavated muck 3 toward the center section (suction pipe 2) with no stagnation even if the conical angle of the cutter head 4 is small, thus the bottom face of a vertical shaft can be made nearly flat. |
