| 摘要 |
<P>PROBLEM TO BE SOLVED: To remove an existing hollow concrete pile by efficiently crushing the existing hollow concrete pile being a hindrance in the construction of a foundation pile, and to crush a lower pile wall as it is even in the presence of an end plate of an intermediate portion of a connecting pile. Ž<P>SOLUTION: A crushing head 1 is constituted by attaching two spiral blades 5 and 5 with crushing blades 10 and 10 to a side surface of a head body 2. The spiral blades 5 and 5 are roationally-symmeteric with respect to a shaft 2b. Each spiral blade 5 is formed in such a shape that an angle of slewing is slightly smaller than an angle of 360°. The spiral blade is formed in such a shape that a diameter becomes gradually larger toward an upper end 7 from a lower end 6, and the lower end 6 is formed in such a shape as to be smaller than an inside diameter of the hollow concrete pile 30. The crushing blade 10 is fixed with a gap 14 to an outer peripheral wall 8 of the spiral blade 5 in such a manner that a cutting edge 12 is directed obliquely downward. A base end 11 of the crushing blade 10 is positioned above a top surface 5b of the spiral blade 5. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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