Pile hole drilling method, pile hole drilling rod

摘要

PROBLEM TO BE SOLVED: To excavate a pile hole with a pile head part efficiently without replacing an excavation head and with about the same amount of discharged soil, the pile hole being excavated to have a diameter Dnear a ground surface greater than a shaft part diameter D.SOLUTION: An excavation rod 30 includes a first mixing drum 20A, a second mixing drum 20B, and a third mixing drum 30C respectively at H, H, and Habove an excavation head 5 (c). A pile hole 42 having a diameter Dis excavated from a ground surface 41 using the excavation head 5, and the pile hole 42 is widened using the first mixing drum 20A to a pile hole 42A with a diameter widened to D(a). Furthermore, the pile hole 42A is widened using the second mixing drum 20B to a pile hole 42B having a diameter D(b), and the pile hole 42B is widened using the third mixing drum 20C to a pile hole 42C having a diameter widened to D(c). The pile hole 42C having the diameter Dnecessary for securing horizontal support force may be formed near the ground surface 41, with the pile hole 42 having the diameter Dat a shaft part necessary for tip supporting force (d).SELECTED DRAWING: Figure 3