METHOD FOR PREVENTING COUNTERFLOW OF EXCAVATED EARTH IN CENTER DRILLING METHOD OF PILE HOLE AND PILE HOLE DRILLING ROD

摘要

PURPOSE: To prevent the counterflow of excavated earth into a pile hole, in a pile-hole drilling rod fitted with a spiral, through the spiral when the pile-hole drilling rod is reversely turned, and to prevent the counterflowed excavated earth from being mixed with cement milk in the consolidation part for forming a strong consolidation part. ;CONSTITUTION: An excavating head 3 is fitted at the end of a drilling rod body 1, and above that a nonspiral part 4 of a prescribed length L is provided, and further above that a spiral 5 for lifting excavated earth is provided. By projectedly providing stirring rods 6 in the radial directions to the nonspiral part 4, a pile-hole excavating head 7 is constituted. And the length L of the nonspiral part 4 is made to be approximately L=2D, where the D is the outside diameter of the pile.;COPYRIGHT: (C)1993,JPO&Japio