Overbreak and Underbreak in Underground Openings Part 2: Causes and Implications
The newly developed light sectioning method has been used to investigate some of the causes and costs of overbreak and underbreak. Investigations at the Aquamilpa Hydroelectric Project in Mexico have shown decreased overbreak and increased underbreak as a result of increased rock quality and decreased explosive energy. A new measure of explosive energy, the 'perimeter powder factor' (PPF), has been defined and shown to be useful in the context of tunnel-wall rock damage. Tentative results indicate that explosive energy (PPF) may be a more important factor in producing underbreak, whereas rock quality may be a greater factor in producing overbreak. A site-specific equation is given for predicting overbreak or underbreak as a function of rock quality and explosive energy, with an evaluation of the cost of underbreak and overbreak.
J. A. Ibarra et al., "Overbreak and Underbreak in Underground Openings Part 2: Causes and Implications," Geotechnical and Geological Engineering, vol. 14, no. 4, pp. 325-340, Springer Netherlands, Dec 1996.
The definitive version is available at http://dx.doi.org/10.1007/BF00421947
Geosciences and Geological and Petroleum Engineering
Keywords and Phrases
Blasting Assessment; Digital Image Processing; Overbreak; Perimeter Powder Factor; Q; RMR; Tunnel Profiling; Tunnelling; Underbreak; Digital Signal Processing; Rock Drilling; Rock Mechanics
International Standard Serial Number (ISSN)
Article - Journal
© 1996 Springer Netherlands, All rights reserved.