To improve workability of a natural slope stabilizing construction method, by reducing the size and weight by reducing a diameter of a double tube hole drilling device, while improving durability of the double tube hole drilling device, by reducing trouble caused when foreign matter such as a granular object and a massive object such as spinning powder is clogged in an engaging part with an outer pipe for connecting an outer bit in a state of allowing only an advance-retreat.
An outer bit side engaging part for allowing only the advance-retreat in the axial direction by engaging with an outer pipe side engaging part 16 formed on an outer pipe 2 side inside surface on the base end part side, is formed on an outer peripheral surface of the outer bit 6. A diametrally contracted part 20 diametrally contracted more than an outer diameter of the outer bit side engaging part, is formed on the tip part side of its outer bit side engaging part. A stopper member 17 lockable on an end part on the tip part side of the outer bit side engaging part and slidable to an outer peripheral surface of the diametrally contracted part 20, is also arranged in a tip part on the outer pipe 2 side.
KIUCHI KAZUO
KATO TAKAAKI
IKEDA TAKEO
NIPPON STEEL METAL PROD
| JP2004278012A | 2004-10-07 | |||
| JP2680433B2 | 1997-11-19 | |||
| JP2001140578A | 2001-05-22 | |||
| JPH09100688A | 1997-04-15 | |||
| JP2001323461A | 2001-11-22 |