| 摘要 |
PURPOSE:To form a pile-forming hole with high excavation efficiency, by a method wherein, after a small pilot hole is excavated, a large casing is pressed in a ground in a condition in that the pilot hole is positioned inside the casing, and residual soil inside the casing is discharged. CONSTITUTION:After a pilot hole 4 is excavated down to a support ground 6 by the use of a screw auger 2, a large casing, having an excavating blade 1a at its forward end, is pressed in a ground, in a state in which the pilot hole 4 is positioned inside the casing, by rotating a large casing 1 as a static load is applied on the forward end thereof. An excavator B is inserted and lowered in the casing 1 in slight delay than press-in of the casing, and excavates unexcavated residual soil within the casing 1 to discharge it. This eliminates a fear of an excess excavating load being applied on the pressing-in casing 1, and enables high efficient formation of a hole for a pile. |
