| 摘要 |
PROBLEM TO BE SOLVED: To provide a spiral rod used in a method of constructing a structure by feeding a bulk cargo simultaneously with press-fitting of the spiral rod, wherein the spiral rod can be effectively driven even into hard ground, and also can be driven at a constant speed even into stratified ground in which soft ground strata and hard ground strata are alternately deposited. SOLUTION: The spiral rod has a transfer screw 2 mounted thereon over an area from a rear end to the vicinity of a front end, and a tip bid 13 mounted at the front end. The tip bid 13 is wound in a direction opposite to that of the transfer screw 2, and has an external diameter smaller than that of the transfer screw 2. COPYRIGHT: (C)2008,JPO&INPIT
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