Method for excavating a tunnel rock face by drilling a pattern of lifter and line holes
US6527345B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | May 10, 2001 |
| Grant date | Mar 4, 2003 |
| Priority date | — |
| Expiry date | Jun 28, 2021 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21D9/006
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
A method for excavating a tunnel rock face by drilling a pattern of lifter holes and line holes. The line holes ensure the grade or slope of the excavation meets specification while reducing the need for cleaning out the face. A longitudinal band of lifter holes is drilled into the tunnel face at an acute angle in relation to the substantially perpendicular reference axis emerging from the tunnel face. A series of line holes, disposed opposedly adjacent to the lifter holes, are drilled at a smaller acute angle. The lifter holes are drilled deeper than the line holes and they do not intersect. Explosives are loaded into the lifter holes. The line holes are expendable and encourage fracturing of the rock.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.