Non-explosive drill hole pressurization method and apparatus for controlled fragmentation of hard compact rock and concrete
US5308149A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 5, 1992 |
| Grant date | May 3, 1994 |
| Priority date | — |
| Expiry date | Jun 5, 2012 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21C37/16
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
Rock and other hard materials, such as concrete, are broken by a controlled-fracturing process referred to as penetrating-cone fracture. The fracturing process is accomplished by pressurizing the bottom of a drill hole in such a way as to initiate and propagate a controlled fracture from the sharp hole-bottom corner while not crushing the surrounding rock. A cartridge containing a propellant charge is inserted at the bottom of a short hole drilled in the rock. The cartridge is stemmed by a massive bar. A firing pin in the stemming bar strikes a primer which then ignites the propellant in the cartridge. The cartridge incorporates a relief volume designed to control propellant burning rates and pressures and thus the pressure at the hole bottom. The cartridge is designed with a tapered wall, which is thicker nearer the stemming bar, and with a large radius of the inside surface of the cartridge base, which reduce the possibility for premature cartridge rupture and loss of propellant generated gases. A sealing mechanism on the stemming bar may also be used to form a seal near the hole bottom. The stemming bar is preferably connected to a boom mounted on a carrier. A preferred embodime…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.