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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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Résultats de recherche

Voici les éléments 1 - 10 sur 13
  • PublicationAccès libre
    Capturing the complete stress–strain behaviour of jointed rock using a numerical approach
    (John Wiley & Sons, Ltd., 2015-01-10) Esmaieli, Kamran; Hadjigeorgiou, John; Grenon, Martin
    This paper presents the results of a series of numerical experiments using the synthetic rock mass (SRM) approach to quantify the behaviour of jointed rock masses. Field data from a massive sulphide rock mass, at the Brunswick mine, were used to develop a discrete fracture network (DFN). The constructed DFN model was subsequently subjected to random sampling whereby 40 cubic samples, of height to width ratio of two, and of varying widths (0.05 to 10 m) were isolated. The discrete fracture samples were linked to 3D bonded particle models to generate representative SRM models for each sample size. This approach simulated the jointed rock mass as an assembly of fractures embedded into the rock matrix. The SRM samples were submitted to uniaxial loading, and the complete stress–strain behaviour of each specimen was recorded. This approach provided a way to determine the complex constitutive behaviour of large-scale rock mass samples. This is often difficult or not possible to achieve in the laboratory. The numerical experiments suggested that higher post-peak modulus values were obtained for smaller samples and lower values for larger sample sizes. Furthermore, the observed deviation of the recorded post-peak modulus values decreased with sample size. The ratio of residual strength of rock mass samples per uniaxial compressive strength intact increases moderately with sample size. Consequently, for the investigated massive sulphide rock mass, the pre-peak and post-peak representative elemental volume size was found to be the same (7 × 7 × 14 m).
  • PublicationAccès libre
    Integrated structural stability analysis for preliminary open pit design
    (ScienceDirect, 2009-11-26) Hadjigeorgiou, John; Grenon, Martin
    A design module has been developed for integrating slope stability analysis into the data management, ore reserve and pit optimisation processes of an open pit mine. The developed slope stability analysis tools were successfully implemented along the full projected pit model of a surface mine in Canada. Undertaken stability analyses included both kinematic and limit equilibrium stability analysis for bench and interramp design. The developed stability analysis modules employed geographical information systems (GIS) techniques to provide visualization tools and establish stability susceptibility zones along the pit. This approach facilitated the selection of acceptable slope design criteria for the pit. A case study was used to illustrate the developed methodology and tools. This approach led to an improved design for the optimised 3D pit configuration and can facilitate communication between the mine planning and geotechnical groups. This can contribute to a better understanding of the economic impact of the different slope and pit design scenarios. Given that open pit design is an iterative process, the opportunity of having design tools that can readily accommodate the use of updated data and explore different options provide tangible economic benefits.
  • PublicationAccès 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, Martin
    The 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.
  • PublicationAccès libre
    Applications of fracture system models (FSM) in mining and civil rock engineering design
    (Taylor & Francis, 2012-01-18) Hadjigeorgiou, John; Grenon, Martin
    Engineering design in rock must, implicitly or explicitly, take into consideration the influence of small and large scale geological fractures. The complexity of a jointed rock mass is best captured using 3D fracture system model based on quality field data. In this article, we describe on-going work in developing and implementing fracture system models (FSM) to solve three engineering problems using the developed stochastic fracture modelling tool, Fracture-SG. The first case study uses field data from 53 mine sites to demonstrate the advantages of using FSM, as compared to empirical classification indices to quantify the structural complexity of a rock mass. The second case describes the determination of a structural representative elemental volume (REV) along a rock slope, and the third case study describes the use of FSM as an integral part of the stability analysis of a slope subject to structural failures.
  • PublicationAccès 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-Luc
    Photogrammetry 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.
  • PublicationAccès libre
    A design methodology for rock slopes susceptible to wedge failure using fracture system modelling
    (Elsevier, 2007-10-23) Hadjigeorgiou, John; Grenon, Martin
    This paper demonstrates how the use of fracture system modelling can be linked to limit equilibrium analysis of rock slopes susceptible to wedge failure. The use of fracture systems highlights some of the limitations inherent in traditional structural data analysis and representation. Consequently it allows for more comprehensive input data that can be used for stability analysis of rock slopes. In particular the developed methodology addresses important issues such as spatial variability and wedge size distributions. The paper introduces a series of guidelines for interpretation of the results of rock slopes. The proposed techniques arguably result in an improved level of confidence in the design of rock slopes susceptible to wedge failure.
  • PublicationAccès libre
    Estimating geometrical and mechanical REV based on synthetic rock mass models at Brunswick Mine
    (ScienceDirect, 2010-06-17) Esmaieli, Kamran; Hadjigeorgiou, John; Grenon, Martin
    This 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.
  • PublicationAccès libre
    Drift reinforcement design based on discontinuity network modelling
    (Pergamon Press, 2003-05-08) Hadjigeorgiou, John; Grenon, Martin
    The 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.
  • PublicationAccès libre
    Practical considerations in establishing the statistical reliability of geomechanical data
    (Chapman & Hall, 2019-07-17) Fillion, Marie-Hélène; Hadjigeorgiou, John; Grenon, Martin; Caumartin, Richard
    In an underground mining operation, the design of safe excavations can be influenced by the quality and quantity of collected geomechanical data. Data collection is the first step in mine design, and a sufficient level of confidence in the input data should be reached depending on the project stage and the design requirements (e.g. temporary and non-entry vs. permanent and entry excavations). This paper compares two statistical analysis methods for quantifying the level of confidence in the intact rock properties obtained through a series of laboratory tests. The laboratory testing database of an underground hard rock mine was used to highlight the variations in the two methods. The impact of the two methods, from an engineering perspective, was illustrated with an example using the Kirsch analytical solution. This investigation demonstrated that the selection of the appropriate analysis method should be guided by the project requirements.
  • PublicationAccès 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, Martin
    This 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.