Personne : Grenon, Martin
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Grenon
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Martin
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Université Laval. Département de génie des mines, de la métallurgie et des matériaux
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ncf10580926
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Publication Accès libre Stability analysis of the 19A ore pass at Brunswick Mine using a two-stage numerical modeling approach(Springer, 2013-01-24) Esmaieli, Kamran; Hadjigeorgiou, John; Grenon, MartinThe longevity of ore pass systems is an important consideration in underground mines. This is controlled to a degree by the structural stability of an ore pass which can be compromised by changes in the stress regime and the degree of fracturing of the rock mass. A failure mechanism specific to ore pass systems is damage on the ore pass wall by impact load or wear by material flow. Structural, stress and material flow-induced failure mechanisms interact with severe repercussions, although in most cases one mechanism is more dominant. This paper aims to provide a better understanding of the interaction of ore pass failure mechanisms in an operating mine. This can provide an aid in the design of ore pass systems. A two-stage numerical approach was used for the back analysis of an ore pass at Brunswick mine in Canada. The first stage in the analysis relied on a 3D boundary element analysis to define the stress regime in the vicinity of the ore pass. The second stage used a synthetic rock mass (SRM) model, constructed from a discrete fracture network, generated from quantitative rock mass field data. The fracture network geometry was introduced into a bonded particle model, in a particle flow code (PFC). Subsequently, the ore pass was excavated within the SRM model. A stability analysis quantified the extent of rock mass failure around the ore pass due to the interaction of pre-existing fractures and the failure of the intact rock bridges between these fractures. The resulting asymmetric failure patterns along the length of the ore pass were controlled to a large degree by the in situ fractures. The influence of particle flow impact was integrated into the model by projecting a discrete rock fragment against the ore pass walls represented by the SRM model. The numerical results illustrated that material impact on ore pass walls resulted in localized damage and accelerated the stress-induced failure.Publication Accès libre Discrete fracture network based drift stability at the Éléonore mine(The Institution of Mining and Metallurgy, 2016-07-05) Hadjigeorgiou, John; Grenon, Martin; Landry, Alex; Lajoie, Pierre-LucPhotogrammetry tools were used to characterise the rock mass structural regime at selected mining drifts at the Éléonore underground mine in Canada. This information was used to provide the input data for generating a series of discrete fracture networks (DFN) models. The generated DFN models were subsequently used to investigate the creation of rock wedges along the drifts that may impact the stability of the excavations. The impact of the choice of employed DFN model on the analysis was investigated with reference to the stability of excavations. A series of parametric analyses demonstrated the sensitivity of the model to variations in the properties of the structural regime. The benefits of using stochastic modelling to capture the inherent variability are reviewed.Publication Accès libre Estimating geometrical and mechanical REV based on synthetic rock mass models at Brunswick Mine(ScienceDirect, 2010-06-17) Esmaieli, Kamran; Hadjigeorgiou, John; Grenon, MartinThis paper uses a case study from Brunswick Mine in Canada to determine a representative elementary volume (REV) of a jointed rock mass in the vicinity of important underground infrastructure. The equivalent geometrical and mechanical property REV sizes were determined based on fracture systems modeling and numerical experiments on a synthetic rock mass. Structural data collected in massive sulphides were used to generate a large fracture system model (FSM), 40 m×40 m×40 m. This FSM was validated and subsequently sampled to procure 40 cubic specimens with a height to width ratio of 2 based on sample width from 0.05 to 10 m. The specimens were introduced into a 3D particle flow code (PFC3D) model to create synthetic rock mass (SRM) samples. The geometrical REV of the rock mass was determined based on the number of fractures in each sampled volume (P30) and the volumetric fracture intensity (P32) of the samples. The mechanical REV was estimated based on the uniaxial compressive strength (UCS) and elastic modulus (E) of the synthetic rock mass samples. The REV size of the rock mass was determined based on a series of statistical tests. The T-test was used to assess whether the means of the samples were statistically different from each other and the F-test to compare the calculated variance. Finally, the coefficient of variation, for the synthetic rock mass geometrical and mechanical properties, was plotted against sample size. For this particular site the estimated geometrical REV size of the rock mass was 3.5 m×3.5 m×7 m, while the mechanical property REV size was 7 m×7 m×14 m. Consequently, for engineering purposes the largest volume (7 m×7 m×14 m) can be considered as the REV size for this rock mass.Publication Accès libre Drift reinforcement design based on discontinuity network modelling(Pergamon Press, 2003-05-08) Hadjigeorgiou, John; Grenon, MartinThe results of structural mapping are used to generate 3-D joint networks. By introducing a virtual excavation in the generated rock mass it is possible to identify all wedges that can potentially be defined at the exposed surfaces of the excavation. The number and size of these wedges are controlled by the geometry and orientation of the excavation, as well as the properties of the generated joint sets and individual random joints. Consequently it is possible to determine the stability of every individual wedge along the span of an excavation. The influence of various reinforcement strategies (type of bolts, reinforcement patterns, mesh, etc.) on the stability of an excavation is quantified. This is a prelude to an economic analysis whereby the costs associated with different stabilization techniques are assessed. This methodology is illustrated by means of three case studies in a polymetallic underground mine in the Canadian Shield.Publication Accès libre Stability analysis of vertical excavations in hard rock by integrating a fracture system into a PFC model(ScienceDirect, 2008-11-20) Esmaieli, Kamran; Hadjigeorgiou, John; Grenon, MartinThis paper presents an implementation of a comprehensive engineering approach to the analysis of the stability of vertical excavations in rock. This approach relies in the generation of discrete fracture systems to better capture the structural complexity of the rock mass. The resulting fracture system is consequently linked into a distinct element stress analysis. The particle flow code was selected as it potentially allows greater flexibility in representing a fracture system. In the first example a 3D fracture system was linked into a 2D PFC model. Although this has allowed for an improved quantification of stress structure interaction it necessitated important simplifications which may not be necessarily appropriate. These have been overcome by providing a complete integration of a 3D fracture system to a 3D PFC model. This will potentially lead into a design tool that adequately account for the stress structure interaction on the stability of vertical or near vertical excavations in hard rock.