Blast Overbreak Measurement by Light Sectioning
In this new method for measuring the cross-section of tunnels and other excavations, the opening is outlined by a plane of light projected from a conical mirror. The image is recorded on videotape, enhanced, then measured by microcomputer. The measured profile is compared automatically with the specified profile to give values for overbreak and underbreak. Trials in Mexican tunnels and at an underground mine in Canada have evaluated the technique in relation to traditional mechanical, photographic, and surveying alternatives. Results indicate that the light sectioning method requires less than a minute per profile and no surveying skills. Costs are low, and the measurements are accurate to within a centimetre or two. Using the same photoanalysis technique and software, rock quality can be measured at the same time and place as overbreak, which helps the engineer to decide whether overbreak is caused by geological conditions or by deficiencies in blasting.
J. A. Franklin et al., "Blast Overbreak Measurement by Light Sectioning," International Journal of Mining and Geological Engineering, vol. 7, no. 4, pp. 323-331, Kluwer Academic Publishers, Dec 1989.
The definitive version is available at http://dx.doi.org/10.1007/BF00896596
Geosciences and Geological and Petroleum Engineering
Keywords and Phrases
Photoanalysis; Rock Blasting; Rock Tunnels; Tunnel Overbreak
International Standard Serial Number (ISSN)
Article - Journal
© 1989 Kluwer Academic Publishers, All rights reserved.