Spathis, AT, Yuill, G & Stow, D 2009, 'Assessment of tunnel perimeters produced by blasting', in PM Dight (ed.), Proceedings of the First International Seminar on Safe and Rapid Development Mining
, Australian Centre for Geomechanics, Perth, pp. 231-238, https://doi.org/10.36487/ACG_repo/902_22
Over break and under break are important measures of conformance to the designed perimeter in a civil or
mine tunnel excavated by blasting. Three randomised paired trials of a new low-density bulk explosive
compared with 70 g/m detonating cord loaded in the perimeter were made in different development headings
of an underground zinc mine. The low-density bulk perimeter explosive produced more over break but less
under break in two of the three comparisons with the detonating cord. However, a statistical analysis on the
small number of paired comparisons indicated insufficient power in a paired t-test and further paired
comparisons are recommended. Rather than the few well defined half-barrels of the detonating cord,
characteristic scorch/crush zones were evident in the low-density bulk explosive rounds and miners observed
somewhat increased barring down time in these blasts. Such observations are understandable due to the
higher effective perimeter charge of the low-density bulk perimeter explosive. The maximum measured over
break was less than 12% and the maximum measured under break was less than 8% for either blasting
system. The miners stated that the speed of loading full faces was faster with the low-density bulk explosive
system, compensating for longer barring-down times. Work is ongoing to improve the low-density bulk
explosive as an alternative for mines seeking rapid development mining and tunnelling.
Box, G.E.P., Hunter, W.G. and Hunter, J.S. (1978) Statistics for Experimenters, John Wiley and Sons, New York,
Brent, G.F. and Noy, M.J. (2005) Matched pairs blasting technique to quantify the benefits of the i-konTM electronic
initiation system, Proceedings of the Third EFEE World Conference on Explosives and Blasting, R. Holmberg
(ed), Brighton, September 13–16, pp. 481–492.
Noy, M.J. and Brent, G.F. (2003) Mine site trialling — experimental design and measurement methods, Orica Technical
Report No. 58635.
Park, H.M. (2008) Hypothesis Testing and Statistical Power of a Test. Technical Working Paper, The University
Information Technology Services (UITS), Center for Statistical and Mathematical Computing, Indiana
Paventi, M., Lizotte, Y., Scoble, M. and Mohanty, B. (1996) Measuring rock mass damage in drifting, Proceedings of
the Fifth International Symposium on Rock Fragmentation by Blasting, B. Mohanty (ed) August 25–29,
Montreal, Canada, A.A. Balkema, Rotterdam, pp. 131–138.
Persson, P-A., Holmberg, R. and Lee, J. (1994) Rock Blasting and Explosives Engineering, CRC Press Inc., Boca
Raton, pp. 265–272.
R Development Core Team (2008) R: A language and environment for statistical computing, R Foundation for
Statistical Computing, Vienna, viewed on 20 February 2009,
Spathis, A.T., Armstrong, L.W. and Lesberg, P.L. (2006) Tunnel blasting using precise electronic delay detonators and
bulk emulsions, Proceedings of the Eighth International Symposium on Rock Fragmentation by Blasting, May
7–11, Santiago, Chile, pp. 411–416.
Stow, D., Yuill, G. and Spathis, A.T. (2008) A Second Implementation of Bulk Perimeter Product, Orica Internal
Technical Report, March.
Stow, D., Yuill, G. and Spathis, A.T. (2006) Blasting Trials of Bulk Perimeter Product, Orica Internal Technical Report
Wetherelt, A. and Williams, D.C. (2006) Using high definition surveying (HDS) to quantify tunnel hole burdens and
fragmentation, Proceedings Eighth International Symposium on Rock Fragmentation by Blasting, May 7–11,
Santiago, Chile, pp. 55–60.
Yamamoto, M., Ichijo, T. and Tanaka, Y. (1995) Smooth blasting with electronic delay detonator, Proceedings Eleventh
Annual Symposium on Explosives and Blasting Research, International Society of Explosives engineers,
February 5–9, Nashville, Tennessee, pp. 144–156.