Citation

Manouchehrian A, Cai M. Can. Geotech. J. 2016; 53(1): 22-34.

Copyright

(Copyright © 2016, National Research Council of Canada)

DOI

10.1139/cgj-2015-0126

PMID

unavailable

Abstract

Rockburst is an unstable rock failure and one of the most hazardous problems in deep hard-rock mines. Before excavation, rocks are loaded under a polyaxial condition. Upon excavation, the rocks at the excavation boundaries are loaded in the tangential direction and unloaded in the radial direction. Understanding rock behaviour under this excavation loading condition is critical for developing measures to control rock failure in underground construction. In this paper, numerical simulation results of unstable rock failure using an explicit finite element tool are presented. Firstly, uniaxial compression tests were simulated to confirm the suitability of the adopted numerical tool for simulating unstable rock failures. Transferred energy ratio (TER) and loading system reaction intensity (LSRI) were proposed as indicators to distinguish between stable and unstable failures. Secondly, unstable rock failures under polyaxial unloading conditions were simulated. The influences of loading system stiffness (LSS), specimen's height to width ratio (H/W), and intermediate principal stress (σ2) on rock failure were investigated. The simulation results showed that rock failure was more violent when the loading system was softer, the specimen was taller, and the confinement was lower. The modelling approach presented in this paper can be useful for predicting unstable rock failure and estimating released kinetic energy, which is important for designing rock support in deep tunnels to control rockburst damage.

Keywords: explicit finite element method, unstable failure, kinetic energy, polyaxial compression, unloading



Les coups de toit sont des phénomènes de rupture de roche instable et constituent les plus grands dangers dans les mines en roche dure. Avant les travaux d'excavation, les roches sont soumises à un chargement multiaxial. Durant ces travaux, les roches situées sur les bords de la mine sont soumises à un chargement tangentiel et le relâchement de charge se fait selon un axe radial. Il est essentiel de bien comprendre le comportement de la roche lors d'une excavation dans de telles conditions de chargement afin de pouvoir mettre en place des mesures visant à limiter la rupture de la roche dans les chantiers souterrains. Dans le présent article, on présente les résultats de simulations numériques de mécanisme de rupture de roche instable, réalisées à l'aide d'une méthode claire, basée sur la méthode des éléments finis. Dans un premier temps, on a simulé des essais de compression uniaxiale pour confirmer la pertinence de la méthode numérique adoptée permettant de simuler les mécanismes de rupture de roche inst...