Post hole excavation method, guide plate null of tip digging head and tip digging

摘要

PURPOSE: To make it possible to minimize the deviation of a pile hole from a predetermined position of a pile and insert the pile with accuracy and ease by guiding a pilot rod with a specified guide board and pilot-drilling based on this guide and then drilling on a full scale. ;CONSTITUTION: A pilot-drilling head 8 for a specified hole is mounted to the lower end of a drilling rod 6 while the drilling rod 6 is lowered after it is connected to the base end of a pilot-drilling rod 7. Then, the lower end of the pilot-drilling rod is inserted into a guide cylinder 1 and the drilling rod 6 is rotated so as to pilot-drill and shield, which provides a pilot-hole 10 for the specified hole. Then, the pilot-drilling rod 7 and the pilot-drilling head are removed and connected to a drilling head 11 for excavation. In this case, the drilling head 11 is aligned with the pilot-drilling hole for the specified hole while a veneering drum 12 serves as a guide, which makes it possible to protect a pile hole 10a from bending.;COPYRIGHT: (C)1993,JPO&Japio