| 摘要 |
PROBLEM TO BE SOLVED: To excavate the ground of different soil properties by means of a single excavator without using any large-scale device. SOLUTION: A cutter head 3 provided with fixed cutter bits (a tool bit 20, an advance bit 21) and movable disc cutters 18, 19 is used. In excavation of a sediment-viscous soil layer, the blade edges of all the disc cutters 18, 19 are retracted from those of the cutter bits 20, 21 for excavating a facing. In excavation of a sand-rock layer, the cutter edges of all the disc cutters 18, 19 are protruded beyond those of the cutter bits 20, 21 for excavating a facing. |
