| 摘要 |
PROBLEM TO BE SOLVED: To efficiently excavate a pile hole by reducing a load on an excavating head; to reduce removed earth by reducing the amount of the removed earth to be almost equivalent to the amount of cement milk charged into a foot protection layer; and to achieve the less amount of the removed earth in a smaller excavation diameter, particularly in the case of a special shaped pile. SOLUTION: The excavating rod 40 is constituted by connecting a lower rod 10, which is fitted with a mud-sticking drum 18, and the excavating head 1 to a lower end of an upper rod 35 with a normal mud-sticking drum 38. In the drum 18, protrusive streaks 30 are juxtaposed on a mud-sticking surface in a go-around direction. Excavation is performed in a diameter D<SB>1</SB>without injection of water by using fixed excavating blades 5 and 5a of the excavating head 1. The protrusive streaks 30 of the drum 18 of the lower rod 10 makes a pile hole wall excavated in the state of being further expanded up to a diameter D<SB>4</SB>, and the excavated earth is pushed into the pile hole wall and leveled off. The pile hole wall is also leveled off in a diameter D<SB>3</SB>by using the upper rod 35. After the completion of the excavation of an axial part 42 of the pile hole with a diameter D<SB>2</SB>(=D<SB>4</SB>), the foot protection layer is formed, and a prefabricated pile (with a maximum outside diameter D<SB>2</SB>) is buried in the pile hole, so that a foundation pile structure can be constructed. COPYRIGHT: (C)2005,JPO&NCIPI
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