Blast-induced damage and its impact on structural stability of underground excavations
Uticaj miniranja na strukturnu stabilnost podzemnih prostorija
Abstract
Analysis of rock wedge stability plays important role in tunneling and hard rock mining. Today there are many procedures for prediction of wedge formation and their stability. These procedures consider preexisting joints in rock mass, and there is no procedure that considers blast-induced cracks and their impact on structural stability of excavations. Using main principles of new rock blasting theory it is possible to assess length and density of radial cracks around blastholes. Herein, one simple excavation situation in hard rock is presented, where only two joint sets were present. This made it impossible for rock wedges to form. After blast-induced crack with limited persistence was added to analysis as result unstable rock wedge was formed. in addition to presented problem it is suggested how mechanical properties of blast-induced cracks could be estimated using Barton-Bandis failure criterion. As final result it was clear that without blast- induced cracks no wedge stability analysis is complete.
References
CRAWFORD, A. M. and BRAY, J. W. (1983) Influence of in-situ stress field and joint stiffness on rock wedge stability in underground openings. Canadian Geotechnical Journal, 20(2), pp. 276-287.
ELMOUTTIE, M., POROPAT, G. and KRÄHENBÜHL, G. (2010) Polyhedral modelling of underground excavations. Computers and Geotechnics, 37(4), pp. 529-535.
GOODMAN, R.E. and SHI G.H. (1985) Block Theory and Its Application to Rock Engineering. Englewood Cliffs, New Jersey: Prentice-Hall.
GRENON, M. et al. (2016) Discrete fracture network based drift stability at the Éléonore mine. Mining Technology. Available from http://www.tandfonline.com/loi/ymnt20
MALMGREN, L. and NORDLUND, E. (2006) Behaviour of shotcrete supported rock wedges subjected to blast-induced vibrations. International Journal of Rock Mechanics and Mining Sciences, 43(4), pp. 593-615.
ROCSCIENCE INC. (2003) Unwedge - Underground Wedge Stability Analysis, [Software], version 3.0, Toronto: Rocscience.
SOFIANOS, A.I. (1986) Stability of rock wedges in tunnel roofs. International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts, 23(2), pp. 119-130
TORBICA, S. and LAPCEVIC, V. (2014a) Rock breakage by explosives. European International Journal of Science and Technology, 3(2), pp. 96-104.
TORBICA, S. and LAPCEVIC, V. (2014b) Model for estimating blasted rock fragmentation. In: Proceedings of 14th SGEM GeoConference on Science and Technologies In Geology, Exploration and Mining. Albena, June 19-25. Albena: SGEM: Surveying Geology & mining Ecology Management, pp. 379-386.
TORBICA, S. and LAPČEVIĆ, V. (2015) Estimating extent and properties of blast- damaged zone around underground excavations. Rem: Revista Escola de Minas, 68(4), pp. 441–453.
