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  • 1
    Electronic Resource
    Electronic Resource
    Overbreak and underbreak in underground openings Part 2: causes and implications (1996)
    Springer
    Geotechnical and geological engineering 14 (1996), S. 325-340 
    Details
    ISSN: 1573-1529
    Keywords: overbreak ; underbreak ; digital image processing ; tunnelling ; blasting assessment ; tunnel profiling ; RMR ; Q ; powder factor ; perimeter powder factor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Summary 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00421947
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Overbreak and underbreak in underground openings Part 1: measurement using the light sectioning method and digital image processing (1996)
    Springer
    Geotechnical and geological engineering 14 (1996), S. 307-323 
    Details
    ISSN: 1573-1529
    Keywords: overbreak ; underbreak ; digital image processing ; tunnelling ; blasting assessment ; tunnel profiling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Summary Quick, simple, reliable, and inexpensive measurements of overbreak and underbreak are needed for proper evaluation of tunnelling by the drill and blast method. Problems causing rock damage can be identified and remedied while the work is still in progress. The measurements are also useful in identifying causes of overbreak and overbreak, and in helping to settle contractual disputes relating to payment for replacement concrete and secondary blasting of ‘tights’ (zones of underbreak). A newly developed method to measure underbreak and overbreak is presented here. The light sectioning method (LSM) uses a radial sheet of light to define the tunnel profile. An image of the final tunnel profile is acquired and digitized, using digital image analysis. This profile is superimposed over the design profile, and from this zones of overbreak and underbreak are identified, quantified, and presented graphically.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00421946
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
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