References of "Collin, Frédéric"
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See detailCaractérisation minéralogique, géochimique et géotechnique des matières premières utilisées en poterie dans le site d’Agafay, Marrakech, Maroc.
El Boudour El Idrissi, Hicham; Daoudi, Lahcen; El Ouahabi, Meriam ULg et al

Conference (2014, April 03)

Le site potier d’Agafay est localisé à 20 km au S-W de la ville de Marrakech, à l’ouest de l’oued N’Fis. L’activité potière y a débuté par transfert du savoir-faire à partir du village de Tamsloht vers ... [more ▼]

Le site potier d’Agafay est localisé à 20 km au S-W de la ville de Marrakech, à l’ouest de l’oued N’Fis. L’activité potière y a débuté par transfert du savoir-faire à partir du village de Tamsloht vers 1940 apr. J.-C. Le site comporte environ 90 ateliers où sont actifs 240 artisans. Les principales pièces produites sont les gasriyas (i.e., plats traditionnels de couscous et de modelage de pâtes de pains) et les briques des grandes murailles traditionnelles. Les matières premières utilisées, brutes ou en mélange, sont issues des terres agricoles locales (Ag1 et Ag5) pour les gasriyas et des dépôts actuels du oued N’Fis (Ag7) pour les briques. Les problématiques rencontrées dans ce site concernent les deux types de produits, gasriyas et briques. Dans le premier cas, des grains de la chaux gonflent dans les pièces après le contact prolongé des pièces produites avec l’air. Ce gonflement engendre des décollements dans les tessons et nuit à la qualité du produit final. Dans le deuxième cas, la distribution non homogène de la chaleur à l’intérieur des fours traditionnels utilisés engendre une très grande variation de couleur dans les briques, elles sont généralement tordues et certaines fondent totalement. Notre projet vise à une caractérisation scientifique des différentes phases de fabrication afin de remédier à ces problèmes. Les résultats montrent que la composition chimique est surtout silico-alumineuse (55 à 61 % de SiO2 ; 16 à 20% d’Al2O3), la teneur en Fe2O3 se situe entre 6 et 8 %, celle de CaO ne dépasse pas 6% pour les pâtes des gasriyas et atteint 10 % pour les pâtes des briques. La teneur en carbonates mesurée par le calcimètre de Bernard varie entre 5 et 14 %. La teneur en matière organique varie entre 5 et 7,5 %. L’indice de plasticité oscille entre 16 et 17,5. Pour des teneurs en eau proches de la limite de plasticité le degré de retrait au séchage des gasriyas est de l’ordre de 5 %, il est plus élevé pour les briques (8%) ce qui nécessite une plus grande maitrise du processus de séchage pour éviter que les pièces ne se tordent pas. La granulométrie des pâtes utilisées pour les gasriyas a montré une teneur moyenne de 50 % pour les argiles, 32 % pour les limons et 18 % pour les sables. Les briques comportent une proportion égale des trois classes granulométriques. La minéralogie de l’ensemble des pâtes est formée de quartz (< 27%), plagioclase (13%), calcite (7 à 9%), dolomite (5%) et argile (50%, 34% et 34% pour Ag1, Ag5 et Ag7, respectivement). Le feldspath potassique est présent uniquement dans l’échantillon Ag7. Concernant la fraction argileuse, elle est surtout constituée d’illite pour l’ensemble des pâtes, associée à des interstratifiés irréguliers 14c-14s (13 %) pour la pâte des briques, et une teneur de 11 % de smectite pour la pâte des gasriyas (Ag5). La mesure de la vitesse sonique a montré que les pièces formées par pression aboutissent à une porosité moindre que celle des pièces produites par boudinage. La densité des pièces produites reste semblable pour les cuissons à 950°C et 1050°C. Le plus bas degré de porosité ainsi que les plus grandes valeurs de résistance mécanique à la compression ont été enregistrés sur les pièces cuites à 1050 °C. Les contraintes maximales atteintes se situent entre 51 et 59 MPa pour les gasriyas et 24,5 MPa pour les briques. Quant à la résistance mécanique à la flexion, elle varie entre 17,4 et 20,3 N/mm² pour les gasriyas et 9,4 N/mm² pour les briques. L’analyse DRX des pièces cuites à 1050 °C a montré la disparition totale des carbonates et des argiles à cette température, accompagnée de l’apparition de la géhelénite, cristobalite, anorthoclase, diopside, spinelle et hématite. A l’issue de cette étude, nous recommandons un tamisage humide à 1 mm pour réduire l’effet des gros grains de la chaux, une cuisson par palier jusqu’à 1050°C est également nécessaire pour comprendre les transformations des phases minéralogiques et vitreuses. Finalement, l’utilisation des fours équipés d’une sonde pour garantir une meilleure distribution de la chaleur. [less ▲]

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See detailHollow Cylinder Tests on Boom Clay: Modelling of Strain Localization in the Anisotropic Excavation Damaged Zone
François, B; Labiouse, V; Dizier, A et al

in Rock Mechanic and Rock Engineering (2014), 47(1), 71-86

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See detailAn unsaturated hydro-mechanical modelling of two in-situ experiments in Callovo-Oxfordian argillite
Charlier, Robert ULg; Collin, Frédéric ULg; Pardoen, Benoît ULg et al

in Engineering Geology (2013), 165

The unsaturated behaviour of Callovo-Oxfordian argillite is investigated through the modelling of 2 in-situ experiments. The first test studies the influence of ventilation in a gallery on the hydro ... [more ▼]

The unsaturated behaviour of Callovo-Oxfordian argillite is investigated through the modelling of 2 in-situ experiments. The first test studies the influence of ventilation in a gallery on the hydro-mechanical behaviour of the rock mass. The second test consists in a gas injection in the rock mass from an experimental borehole. A hydro-mechanical model is described and used in the modelling of the experiments. A review of the main hydro-mechanical parameters of argillite is presented. The numerical results highlight the need of a flow boundary condition reproducing the fluid transfers between the surroundings and the rock mass. The influence of dissolved gas on the compressibility of the liquid phase is also emphasised. [less ▲]

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See detailModelling hydro-mechanical coupling using a FE² doublescale approach
van den Eijnden, Abraham Pieter ULg; Collin, Frédéric ULg; Bésuelle, Pierre et al

Scientific conference (2013, September 11)

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See detailA double-scale modelling approach for hydro-mechanical coupling
van den Eijnden, Abraham Pieter ULg; Collin, Frédéric ULg; Bésuelle, Pierre et al

Scientific conference (2013, August 22)

An approach is investigated for the modelling of the hydro-mechanical coupled behaviour of Callovo-Oxfordian claystone, a potential host rock for radioactive waste repositories in France. This approach is ... [more ▼]

An approach is investigated for the modelling of the hydro-mechanical coupled behaviour of Callovo-Oxfordian claystone, a potential host rock for radioactive waste repositories in France. This approach is a double-scale finite element method, distinguishing a micro and a macro scale. At the micro level a representative elementary volume (REV) is used to model the material behaviour. The global response of this REV serves as an implicit constitutive law for the macro scale. On the macro scale, a poro-mechanical continuum is defined with fully coupled hydro-mechanical behaviour, the micro scale contains a model that takes into account the material micro structure to provide the material response to deformation and the associated stiffness matrices. Computational homogenization is used to retrieve the macro tangent stiffness from the micro level. This double scale approach is applied in the simulation of biaxial deformation tests, demonstrating the possibility of using the double scale modelling approach with the presented model at the micro level. The response at the macro level is compared with the micro-mechanical behaviour. [less ▲]

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See detailModelling the excavation damaged zone in claystone with strain localisation using coupled second gradient model and the influence of gallery ventilation
Pardoen, Benoît ULg; Levasseur, Séverine ULg; Collin, Frédéric ULg

Conference (2013, July 09)

Drilling of galleries induces stress perturbations that trigger damage propagation in the surrounding medium. The excavation process creates then the so-called excavation damaged zone around the galleries ... [more ▼]

Drilling of galleries induces stress perturbations that trigger damage propagation in the surrounding medium. The excavation process creates then the so-called excavation damaged zone around the galleries. The prediction of the extension and of the fracture structure within this zone remains nowadays a major issue especially in the context of underground storage. Since localised deformation in shear band mode is frequently observed in experimental works, the excavation damaged zone can be modelled by considering the development of shear strain localisation bands. To correctly model this behaviour, an enhanced model with a regularisation method is required. In underground structures, air ventilation inside the galleries induces a rock-atmosphere interaction that may lead to drainage and to rock desaturation close to the gallery wall. Such desaturation may influence the damage zone structure and needs to be studied. A hydro-mechanical modelling of a gallery excavation including air ventilation is thus performed and the numerical results provide information about the damaged zone extension, the strain localisation bands pattern and the influence of rock desaturation. [less ▲]

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See detailStrain localization modeling in coupled transient phenomena
Collin, Frédéric ULg; Sieffert, Yannick; Chambon, René

in Laloui, Lyesse (Ed.) Mechanics of Unsaturated Geomaterials (2013)

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See detailHydromechanical coupling theory in unsaturated geomaterials and its numerical integration
Charlier, Robert ULg; Radu, Jean-Pol ULg; Gerard, Pierre ULg et al

in Laloui, Lyesse (Ed.) Mechanics of Unsaturated Geomaterials (2013)

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See detailComputational homogenization for hydro‐mechanical coupling in multi‐scale modelling, FEM x FEM
van den Eijnden, Abraham Pieter ULg; Bésuelle, Pierre; Chambon, René et al

Scientific conference (2013, January 31)

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See detailPossibilities and limitations of the Prevost model for the modelling of cohesionless soil cyclic behaviour
Cerfontaine, Benjamin ULg; Charlier, Robert ULg; Collin, Frédéric ULg

in Proceedings of the 18th International Conference on Soil Mechanics and Geotechnical Engineering (2013)

The Prevost’s model is currently used to model cyclic behaviour of soils especially in earthquake engineering. The original model is able to capture the main features of cyclic behaviour: pore pressure ... [more ▼]

The Prevost’s model is currently used to model cyclic behaviour of soils especially in earthquake engineering. The original model is able to capture the main features of cyclic behaviour: pore pressure build up and plastic deformation accumulation. But accurate modelling of laboratory tests requires improvements. Enhanced models exist but require a lot of parameters that make them cumbersome for practical purpose. A suction caisson, part of a tripod offshore foundation for wind turbines is modelled. Possibilities of the Prevost’s model are highlighted compared with a classical Drucker-prager model. [less ▲]

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See detailOn micromechanical damage modeling in geomechanics: influence of numerical integration scheme
Levasseur, Séverine ULg; Collin, Frédéric ULg; Charlier, Robert ULg et al

in International Journal of Computational & Applied Mathematics (2013), 246

Tunnel excavations in deep rocks provide stress perturbations which initiate diffuse and/or localized damage propagation in the material. This damage phenomenon can lead to significant irreversible ... [more ▼]

Tunnel excavations in deep rocks provide stress perturbations which initiate diffuse and/or localized damage propagation in the material. This damage phenomenon can lead to significant irreversible deformations and changes in rock properties. In this paper, we propose to model such behavior by considering a micromechanically-based damage approach. The resulting micromechanical model, which also accounts for initial stress, is described and assessed through the numerical analysis of a synthetic tunnel drilling in Opalinus Clay. A particular emphasis is put on the numerical integration of the model. In particular, an appropriate choice of the latter is required to ensure the numerical stability and a confident prediction of excavation damaged zone around tunnels. [less ▲]

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See detailA micro–macro approach of permeability evolution in rocks excavation damaged zones
Levasseur, Séverine ULg; Collin, Frédéric ULg; Charlier, Robert ULg et al

in Computers & Geotechnics (2013), 49

Excavation damaged zone, with significant irreversible deformations and nonnegligible changes in flow and transport properties generally occurs in indurated clay around underground structures. The stress ... [more ▼]

Excavation damaged zone, with significant irreversible deformations and nonnegligible changes in flow and transport properties generally occurs in indurated clay around underground structures. The stress perturbation around the excavation could lead to a significant increase of the permeability physically due to diffuse and/or localized microcracks growth in the material. In the present study, we investigate microcracks-induced damage processes together with the subsequent modification in permeability. The proposed approach is based on a homogenization-based upper bound extended to the context of micro-cracked media in presence of initial stress. Application of this approach is done on a borehole excavation problem related to the Selfrac in situ experiments on Opalinus Clay. Although, the model fails to quan-titatively account for the in situ permeability change (which may also originated from existing macro-fractures), its prediction shows a significant evolution of the material permeability around the borehole. This is in qualitative agreement with available data. [less ▲]

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See detailModelling the excavation damaged zone in Callovo-Oxfordian claystone with strain localization
Pardoen, Benoît ULg; Collin, Frédéric ULg; Levasseur, Séverine ULg et al

Conference (2012, October)

Gallery excavation in clayey rocks induces stress perturbations that trigger damage propagation. The excavation process creates then the so-called excavation damaged zone in which properties are modified ... [more ▼]

Gallery excavation in clayey rocks induces stress perturbations that trigger damage propagation. The excavation process creates then the so-called excavation damaged zone in which properties are modified. The prediction of the extension and especially of the fracturing structure in this zone remains a crucial issue in the context of underground storage. Since strain localization in shear band mode is frequently observed in experimental works, the excavation damaged zone can be modeled by considering the development of strain localization bands. A hydro-mechanical modelling of a gallery excavation is performed. The numerical results exhibit an excavation damaged zone extension similar to the in situ measurements and provides information about the rock state within this zone. [less ▲]

Detailed reference viewed: 24 (13 ULg)