Overbreak and Underbreak in Underground Openings Part 2: Causes and Implications

Abstract

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.

Department(s)

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)

0960-3182

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 1996 Springer Netherlands, All rights reserved.

Publication Date

01 Dec 1996

Link to Full Text

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