| 摘要 |
PROBLEM TO BE SOLVED: To avoid the collapse of the wall of a bore hole made in advance by forming a pile for holding a loose bore hole wall to a depth at the lower end in a hard stratum in advance and then forming a pile-shaped or wall-shaped thing such as a sand pile or a hardened pile in the pile portion. SOLUTION: A casing pipe 12 is rotated by a motor 14 and inserted to a bottom portion 16 in a hard stratum 1. Next, sand is placed from a sand inlet 11 and inserted to the casing pipe 12, then the casing pipe 12 is pulled out, sand is left in the bore hole portion, and a sand pile 15 is formed in the ground. Then, an insertion pipe 23 is rotated in alignment with the center of a column body working the tip of a mechanical type agitator equipment 30. Then, agitating vanes are rotated while discharging a low strength hardener from the tip of the insertion pipe 23, and is driven while mixing together with the excavated earth, and the discharging is stopped at design depth of 29. In succession, the insertion pipe 23 is rotated reversely and pulled up while mixing and agitating thereby forming a columnar body 25 including both the soft ground 2 and the hard stratum 1. In this way, the penetration of the insertion pipe can be made easier, thereby permitting the high efficiency work for piles or wall-shaped things such as sand piles, crushed stone piles or the like required.
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