| 摘要 |
PROBLEM TO BE SOLVED: To provide an enlarged excavating bit capable of securely providing a specified enlarged excavating diameter even in any ground including a hard ground such as mudstone and a large enlarged excavating diameter by suppressing an excavating resistance in enlarged excavation. SOLUTION: In a pile installation by inner excavation, the enlarged excavating bit 12 fitted to the tip part of a screw auger 11 comprises an excavating blade 15 in the form of a fixed blade and an opening/closing type enlarged blade 16. The enlarged blade 16 is formed to be enlarged larger than the outer diameter of an existing pile 10 in the projected state of the exiting pile 10 from the tip part thereof. Also, the bit comprises a nozzle 17 jetting water toward the side of the screw auger 11. As necessary, high-pressure water is jetted from the nozzle 17 in a direction perpendicular to the axis of the screw auger 11. COPYRIGHT: (C)2005,JPO&NCIPI
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