Zhang, P, Yi, CP, Nordlund, E, Shirzadegan, S, Nyberg, U, Malmgren, L & Nordqvist, A 2013, 'Numerical back-analysis of simulated rockburst field tests by using coupled numerical technique', in Y Potvin & B Brady (eds), Proceedings of the Seventh International Symposium on Ground Support in Mining and Underground Construction
, Australian Centre for Geomechanics, Perth, pp. 565-581, https://doi.org/10.36487/ACG_rep/1304_39_Zhang
In order to assess the capacity of ground support systems when submitted to dynamic loading, simulated rockburst tests utilising blasting have been performed for many years in different countries with limited success. In general, the blasts need to be carefully designed in order to reach the goal; however, different blast layouts, e.g. blasthole angle, burden, have been used based on researcher’s experience without conducting detailed analyses, the exception being a field test by CSIR. Recently, field trials have been conducted at the LKAB Kiirunavaara underground mine with some unexpected results which show that either the whole tested panel was destroyed or only a few fractures were formed without any ejections being observed. The aim of this paper is to investigate the failure mechanism in the simulated rockburst tests and improve the blast design by back-analysing the test results using a coupled numerical modelling technique. The blast was simulated by using finite element method (LS-DYNA) and the dynamic interaction between the blasting generated waves and the opening was simulated by using discrete element modelling (UDEC) with the dynamic input from LS-DYNA. The numerical modelling showed that blasting can create both radial fractures radiating from the blasthole and fractures parallel or subparallel to the surface of the tested panel caused by reflected tensile stress waves. By comparing the results of the numerical modelling with the measured data, it is shown that the collapse failure was mainly controlled by the creation of a cone-shaped area formed by radial fractures and the burden seems to be a critical factor. In order to obtain fractures caused by reflected tensile stress waves and reduce blasting induced radial fractures, two parallel blastholes are suggested with larger burden (> 5 m) for future tests. Furthermore, the limitation of the current numerical modelling has also been discussed. The coupled numerical technique has shown its advantage when simulating blasting as well as interaction between waves and opening and it can thus be used as a tool for extrapolating results from simulated rockburst experiments if detailed geological structure and ground support systems can be incorporated in the model and the model can be well calibrated.
Andrieux, P., Turichshev, A., O’Connor, P. and Brummer, R.K. (2005) Dynamic testing with explosive charges of rockburst-resistant ground support systems at the Fraser Nickel Mine, Itasca Consulting Canada Inc Report to Falconbridge Limited Mine Technical Services; Final Version, September 2005, Sudbury, Canada, 102 p.
Archibald, J.F., Baidoe, J.P. and Katsabanis, P.T. (2004) Rockburst damage mitigation benefits deriving from use of spray-on rock linings, Surface Support in Mining, Y. Potvin, T.R. Stacey and J. Hadjigeorgiou (eds), Australian Centre for Geomechanics, Perth, pp. 169–178.
Borrvall, T. and Riedel, W. (2011) The RHT concrete model in LS-DYNA, in Proceedings Eighth European LS-DYNA users conference, 23–24 May, Strasbourg, France, 14 p.
Bouamoul, A. and Nguyen-Dang, T.V. (2008) High explosive simulation using arbitrary Lagrangian-Eulerian formulation, Technical Memorandum, Defence R&D Canada, Valcartier, Canada, 34 p.
Brandshaug, T. (2009) An initial evaluation of the effects of seismic motion on a footwall drift at LKAB’s Kiirunavaara mine, Internal Report, LKAB, Sweden, 36 p.
Dahner, C., Malmgren, L. and Bošković, M. (2012) Transition from non-seismic mine to a sesmically active mine: Kiirunavaara Mine, in Proceedings Eurock 2012, Befo (ed), 28–30 May 2012, Stockholm, Sweden, CD-Rom only.
Espley, S.J., Heilig, J. and Moreau, L.H. (2004) Assessment of the dynamic capacity of liners for possible application in highly stressed mining environments at Inco limited, Surface Support in Mining, Y. Potvin, T.R. Stacey and J. Hadjigeorgiou (eds), Australian Centre for Geomechanics, Perth, pp. 187–192.
Hadjigeorgiou, J. and Potvin, Y. (2007) Overview of dynamic testing of ground support, in Proceedings Fourth International Seminar on Deep and High Stress Mining (Deep Mining 07), Y. Potvin (ed), 7‒9 November 2007, Perth, Australia, Australian Centre for Geomechanics, Perth, pp. 349–371.
Hagan, T.O., Milev, A.M., Spottiswoode, S.M., Hildyard, M.W., Grodner, M.A., Rorke, J., Finnie, G.J., Reddy, N., Haile, A.T., Le Bron, K.B. and Grave, D.M. (2001) Simulated rockburst experiment – an overview, The Journal of The South African Institute of Mining and Metallurgy, August 2001, pp. 217–222.
Hallquist, J. (2006) LS-DYNA theory manual, Livermore software technology corporation, Livermore, California, 680 p.
Heal, D. and Potvin, Y. (2007) In-situ dynamic testing of ground support using simulated rockbursts, in Proceedings Fourth International Seminar on Deep and High Stress Mining (Deep Mining 07), Y. Potvin (ed), 7‒9 November 2007, Perth, Australia, Australian Centre for Geomechanics, Perth, pp. 373–394.
Helte, A., Lundgren, J., Örnhed, H. and Norrefeldt, M. (2006) Prestandabestämning av svensk sprängdeg m/46, Rapport nr FOI-R-2051-SE, FOI, Stockholm, Sweden.
Itasca Consulting Group (2011) UDEC-Universal Distinct Element Code, Version 4.01, User Manual, Minnesota, USA.
Kaiser, P.K., McCreath, D.R. and Tannant, D.D. (1996) Canadian rockburst support handbook, Geomechanics Research Centre, Sudbury, 300 p.
Malmgren, L. and Nordlund, E. (2008) Interaction of shotcrete with rock and rock bolts—A numerical study, International Journal of Rock Mechanics & Mining Sciences, Vol. 45, pp. 538–553.
Malmgren, L. and Sjöberg, J. (2006) Bergmekaniska analyser för ny huvudnivå i KUJ (1365), Utredning nr 06-797, LKAB, Sweden.
Olsson, M., Nyberg, U. and Fjellborg, S. (2009) Kontrollerad sönderbrytning vid skivrassprängning - inledande försök, Swebrec report 2009:2, Swedish Blasting Research Centre, Stockholm, Sweden.
Ortlepp, W.D. (1992) Implosive-load testing of tunnel support, Rock Support in Mining and Underground Construction, Kaiser, P.K. and McCreath, D.R. (eds), Balkema, Rotterdam, pp. 675–682.
Riedel, W., Thoma, K., Hiermaier, S. and Schmolinske, E. (1999) Penetration of reinforced concrete by BETA-B-500, numerical analysis using a new macroscopic concrete model for hydrocodes, in Proceedings Ninth International Symposium on Interaction of the Effects of Munitions with Structures, SKA (ed), 3–7 May 1999, Berlin-Strausberg, Germany, pp. 315–322.
Schill, M. (2012) Finite element simulations of blasting and the effects of precise initiation on fragmentation, Swebrec report, Luleå University of Technology, Sweden.
Shirzadegan, S., Nordlund, E., Nyberg, U., Zhang, P., Malmgren, L. and Nordqvist, A. (2013) Rock support subjected to dynamic loading: field testing of ground support using simulated rockburst experiment, Research report, Luleå University of Technology, Sweden.
Stacey, T.R. (2012) A philosophical view on the testing of rock support for rockburst conditions, The Journal of The Southern African Institute of Mining and Metallurgy, Vol. 112, August 2012, pp. 703–710.
Tannant, D.D., Brummer, R.K. and Yi, X. (1995) Rockbolt behaviour under dynamic loading: field tests and modelling, International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts, Vol. 32, pp. 537–550.
Zhang, P. and Yi, C.P. (2013) Coupled finite element and discrete element modeling of simulated rockburst tests at the Kiirunavaara underground mine, Research report, Luleå University of Technology, Sweden.