| 摘要 |
PROBLEM TO BE SOLVED: To easily, smoothly and positively expand a blade in a diameter enlarging excavating apparatus and a construction method of a pipe pile suitable for a steel pipe pile construction method by so-called inner excavation foot protection. SOLUTION: A main expansion plate 82 and an auxiliary expansion plate 90 are provided on the tip side of expansion blades 73, 73, respectively. The auxiliary expansion plate 90 has an expansion lock function of keeping the expansion blade 73 in a contracted attitude by a fastening part 91, and a function of expanding the expansion blade to the extent of releasing lock in a rotating direction by a recess 82a of the main expansion plate 82 by the push-up action of a large diameter part 92. The main expansion plate 90 has the recess 82a for rotating the expansion blade 73 integrally with a rotating shaft, and has a function of actually expanding the expansion blade 73 after auxiliary expansion by the push-up action of the large diameter part 82b. COPYRIGHT: (C)2004,JPO
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