| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for constructing a high-quality field-preparation pile with a spiral projection strip excellent in strength and durability.SOLUTION: A field-preparation pile having a spiral projection strip on an outer peripheral surface, is constructed in the ground by a first process of positioning an excavation head 7 of blocking up a lower end opening part of a steel pipe 6 by a bottom plate, on the ground surface GL of a pile hole excavation position, a second process of excavating a spiral pile hole up to the object depth by rotating-lowering the steel pipe 6 in response to a spiral pitch of a spiral excavation blade 13, a third process of filling a required quantity of pile material in the steel pipe 6 and a fourth process of continuously filling the pile material discharged from an opening part in the pile hole under the spiral excavation blade 13 by opening a bottom plate from the opening part by pressure of the pile material in the steel pipe 6 in the vicinity of a pile hole bottom part, by reversing-raising the steel pipe 6 so that the spiral excavation blade 13 traces a spiral pile hole inner peripheral surface formed in the second process in a state of pressurizing an upper surface of the pile material in the steel pipe 6 by compressed air.SELECTED DRAWING: Figure 1 |
