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Civil-Comp Proceedings
ISSN 1759-3433
CCP: 89
PROCEEDINGS OF THE SIXTH INTERNATIONAL CONFERENCE ON ENGINEERING COMPUTATIONAL TECHNOLOGY
Edited by: M. Papadrakakis and B.H.V. Topping
Paper 164

Prediction of Rock Burst in Elastic-Brittle-Plastic Rock

S.K. Sharan

School of Engineering, Laurentian University, Sudbury, Ontario, Canada

Full Bibliographic Reference for this paper
S.K. Sharan, "Prediction of Rock Burst in Elastic-Brittle-Plastic Rock", in M. Papadrakakis, B.H.V. Topping, (Editors), "Proceedings of the Sixth International Conference on Engineering Computational Technology", Civil-Comp Press, Stirlingshire, UK, Paper 164, 2008. doi:10.4203/ccp.89.164
Keywords: rock burst, perturbation, finite elements, brittle plastic rock, underground excavation, unbounded media.

Summary
In this paper, a novel generalized method is developed for the prediction of potential occurrence of rock burst due to the excavation of elastic-brittle-plastic rock. The method is based on a finite element perturbation technique [1].

The problem of rock burst is encountered during or after the excavation of rock for engineering projects such as mining, tunnelling, hydroelectric power generation and disposal of nuclear waste. The sudden and violent expulsion of rock during rock burst may result in fatalities, injuries and heavy economic losses.

A finite element method [1] was recently developed to predict rock burst for axisymmetric problems. In order to generalize the method for two- and three-dimensional problems, a novel integrated loading stiffness parameter is defined in this paper. It is assumed that as the normalized integrated loading stiffness parameter approaches a zero value compared to 1, there is a greater potential of occurrence of rock burst. The rock mass is considered to be governed by the generalized Hoek-Brown failure criterion.

The perturbation is caused by a relatively small incremental excavation around the underground opening. The integrated loading stiffness parameter is expressed in terms of the changes in stresses and displacements resulting from the perturbation. The sampling surface is considered to be the incremental excavation surface and the sampling direction is considered to be normal to the surface.

The effect of the unbounded extent of rock mass around the opening is simulated by using the elastic support method [2]. The results are validated by comparing the finite element results with the recently obtained analytical solutions for the generalized Hoek-Brown failure criterion [3].

Some plane-strain example cases are analyzed to demonstrate the effectiveness of the novel method in predicting rock bursts around a non-circular opening in rock mass subject to hydrostatic and non-hydrostatic in situ stresses. The properties of rock mass used for the example are for a situation where rock bursts have been observed.

The effects of the brittleness, the generalized Hoek-Brown parameter and the dilation parameter of rock mass were found to be highly significant for the potential occurrence of rock burst.

References
1
S.K. Sharan, "A finite element perturbation method for the prediction of rockburst", Computers and Structures, 85, 1304-1309, 2007. doi:10.1016/j.compstruc.2006.08.084
2
S.K. Sharan, "Viscoplastic plane-strain analysis of infinite solids using elastic supports", International Journal for Numerical Methods in Engineering, 45, 355-369, 1999. doi:10.1002/(SICI)1097-0207(19990530)45:3<355::AID-NME594>3.0.CO;2-#
3
S.K. Sharan, "Analytical solutions for stresses and displacements around a circular opening in a generalized Hoek-Brown rock", International Journal of Rock Mechanics and Mining Sciences, 45, 78-85, 2008. doi:10.1016/j.ijrmms.2007.03.002

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