References of "Collin, Frédéric"
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See detailShear banding modelling in cross-anisotropic rocks
Pardoen, Benoît ULg; Seyedi, D.M.; Collin, Frédéric ULg

in International Journal of Solids and Structures (in press)

Sedimentary geomaterials such as rocks frequently exhibit cross-anisotropic properties and their behaviour depends on the direction of loading with respect to their microstructure. As far as material ... [more ▼]

Sedimentary geomaterials such as rocks frequently exhibit cross-anisotropic properties and their behaviour depends on the direction of loading with respect to their microstructure. As far as material rupture is concerned, localised deformation in shear band mode appears generally before cracks and material failure. The influence of cross-anisotropy on the shear strain localisation remains an important issue and is investigated in the present study. To do so, a constitutive elastoplastic cross-anisotropic model that includes anisotropy both on the elastic and plastic characteristics is defined. For the plastic part of the model, the anisotropy of a strength parameter is introduced with a microstructure fabric tensor. Then, the fractures are modelled with finite element methods by considering the development of shear strain localisation bands and an enriched model is used to properly reproduce the shear banding. The cross-anisotropy influence on shear banding is studied through numerical applications of small and large-scale geotechnical problems that engender fractures. The two considered applications are a plane-strain biaxial compression test and an underground gallery excavation. The numerical results provide information about the influence of cross-anisotropy on the appearance and development of shear bands. It has been noticed, among other observations, that the material strength vary with the loading direction and that the development and the shape of the excavation fractured zone that develops around a gallery is strongly influenced by the material anisotropy. [less ▲]

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See detailEfficiency of shaft sealing for CO2 sequestration in coal mines
Bertrand, François ULg; Charlier, Robert ULg; Collin, Frédéric ULg et al

in International Workshop on Geomechanics and Energy: The Ground as Energy Source and Storage (2015, October 13)

This work examined the efficiency of a shaft sealing system for the CO2 sequestration in abandoned coal mines. The particular case of the coal mine of Anderlues was considered. The performed simulation ... [more ▼]

This work examined the efficiency of a shaft sealing system for the CO2 sequestration in abandoned coal mines. The particular case of the coal mine of Anderlues was considered. The performed simulation took into account the anisotropic behaviour of shale and the presence of coalbeds. [less ▲]

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See detailCoupled modeling of Excavation Damaged Zone in Boom clay: Strain localization in rock and distribution of contact pressure on the gallery’s lining
Salehnia, Fatemeh ULg; Collin, Frédéric ULg; Li, Xiang Ling et al

in Computers and Geotechnics (2015), 69

Around galleries excavated at depth in geological media, the creation of a damaged zone with significant irreversible deformation is generally unavoidable. In the case of a geological disposal system for ... [more ▼]

Around galleries excavated at depth in geological media, the creation of a damaged zone with significant irreversible deformation is generally unavoidable. In the case of a geological disposal system for high-level radioactive waste, the resulting change in the host rock properties in this damaged zone may potentially be important with respect to the long-term evolution and the performance of that system. In this context, predicting the extent of the so-called Excavation Damaged Zone (EDZ) and, possibly, the fractures' network topology remains a challenge. This study is aimed to simulate numerically the extension of this zone at the large scale's excavation, around the Connecting gallery (HADES URL, Mol, Belgium), in Boom clay host rock through analyzing the evolution of strain localization in shear bands mode. To realistically model the involved phenomena, the concrete lining is considered on the gallery wall highlighting its impacts on the evolution of convergence and EDZ around the gallery. The focus of the current paper is made on analyzing the coupled hydro-mechanical behavior of Boom clay host rock during and after the gallery excavation with respect to the evolution of localized shear bands around the gallery. This study is accompanied by the analysis of the contact mechanism on the interface between the clay massive and the lining. The obtained results reveal some interesting features regarding the contact phenomenon relatively to the evolution pattern of shear bands within the clay around the gallery. To assess the reliability of the proposed approach, a discussion on some in-situ observations during the gallery's construction is also performed based on which a good agreement is found between the in-situ evidence and simulated results. [less ▲]

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See detailPrediction of the excavation damaged zone in Callovo-Oxfordian claystone using a coupled second gradient model
Collin, Frédéric ULg; Pardoen, Benoît ULg

Scientific conference (2015, July 23)

The solution currently studied in France for long-term management of radioactive waste is the repository in deep argillaceous geological media with low permeability. The drilling of underground galleries ... [more ▼]

The solution currently studied in France for long-term management of radioactive waste is the repository in deep argillaceous geological media with low permeability. The drilling of underground galleries in these clayey rocks induces damage propagation in the surrounding medium. This excavation process creates a damaged zone, in which the material properties are modified. The prediction of the fracture structure and material properties evolution within this zone is a major issue especially in the context of underground disposal. Experimental works have highlighted that the damage around galleries in Callovo-Oxfordian claystone is localized and develops mainly as extensional and shear fractures. We propose to model these shear fractures as a strain localisation process in the mode of a shear band. In order to properly represent the shear strain localisation behaviour, an enhanced model introducing a regularization method and an internal length scale is needed. Among the different regularization methods, the coupled second gradient local model is chosen. To illustrate the development of the damaged zone, a two-dimensional plane strain state hydro-mechanical modelling of a gallery excavation is performed (Lagamine code, ULg) for two orientations of the gallery in the Callovo-Oxfordian claystone. Firstly, a gallery oriented along the minor horizontal principal stress is considered. In this direction, the anisotropy of the stress state in the plane perpendicular to the gallery is the predominant factor leading to the elliptical shape of the damaged zone, with a significantly larger extent in the vertical direction. Secondly, a gallery oriented along the major horizontal principal stress is modelled. The stress state in the plane perpendicular to the gallery is quasi-isotropic and does not lead to shear strain localisation unless the material anisotropy is considered. Moreover, the modelling provides information about the fracture structure and evolution around the gallery. It exhibits a chevron fracture pattern corresponding to in situ experimental measurements of shear fractures for both considered gallery orientations. [less ▲]

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See detailIdentification of the main parameters controlling the plasticity of ceramic pastes: The case study of the Marrakech region (Morocco)
El Boudour El Idrissi, Hicham ULg; Daoudi, Lahcen; Fontaine, François ULg et al

Poster (2015, June 07)

Numerous traditional ceramic workshops occur within a range of 10 to 80 km around the city of Marrakech. Our study aims to identify the main parameters controlling the plasticity of pastes used by the ... [more ▼]

Numerous traditional ceramic workshops occur within a range of 10 to 80 km around the city of Marrakech. Our study aims to identify the main parameters controlling the plasticity of pastes used by the artisans. To reach this goal, we characterize by X-ray diffraction, granulometry and plasticity index (PI) the local raw clayey material. The investigation of 26 whole pastes shows the dominance of quartz (20 to 50%) and clay minerals (25 to 60%) with K-feldspar (2 to 17%), plagioclase (2 to 25%), calcite (0 to 18%), dolomite (0 to 15%), goethite (0 to7%) and trace of hematite and anhydrite (< 3%). Amphibole occurs in trace (< 5%) but only in some samples. The clay minerals are diversified, including illite (10 to 40%), kaolinite (2 to 15%), mixed-layer (ML) (0 to 10%), smectite, vermiculite and chlorite (0 to 5%), and pyrophyllite-talc association (0 to 8%). Sepiolite (12%) is only present in one paste. The grain size is made by variable proportions of sand (5 to 65%), silt (12 to 53%) and clayey fraction (18 to 66%). The Plasticity index (PI) indicates the presence of two principals groups of pastes. (1) The first group is characterized by PI values ranging between 15 to 18. Their moderate plasticity behavior is related either to the low rate of clayey fraction and/or to the absence of plastic clays like smectites and mixed layer with smectitic sheets. (2) The PI of second group ranges between 20 to 32. The high plasticity values are influenced by the presence of specific clayey minerals like talc-pyrophyllite or sepiolite, or by the high content of smectite plus smectitic mixed-layers within the clayey (< 2 micron) fraction. Only one sample without any of these plastic minerals but with a high content of clayey fraction is characterized by a high PI value (24). We concluded that the workability of ceramic paste in Marrakech region is controlled by a combination of factors, dominated by the grain size distribution and the content in plastic clay minerals within the fine fraction. [less ▲]

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See detailMechanical approach for the characterization of loess deposits from the CBR’s Romont quarry (Eben-Emael, Belgium) and correlations with loess stratigraphy
Delvoie, Simon ULg; Boulvain, Frédéric ULg; Cerfontaine, Benjamin ULg et al

Conference (2015, June 01)

Aeolian silts (loess) are near surface deposits covering about 10% of the continent surfaces . Therefore a good knowledge of their mechanical behavior is an issue for designing subsurface engineering ... [more ▼]

Aeolian silts (loess) are near surface deposits covering about 10% of the continent surfaces . Therefore a good knowledge of their mechanical behavior is an issue for designing subsurface engineering structures. Usually this material is considered as homogeneous for an engineering point of view. Aeolian silt deposits are continuously well developed in Hesbaye Region (Belgium) reaching locally 20m thick (see document in attachment). They are mainly related to the last interglacial (Eemian) and glacial (Weichselian) periods . Nevertheless the pedostratigraphical, chronostratigraphical and paleoclimatic approaches have shown these silt deposits are usually composed of a series of paleosoils (i.e. Rocourt soil, Humiferous Complex of Remicourt, Harmignies Soil, Nagelbeek Tongued Horizon) interbedded with stratified or homogeneous aeolian silt layers. This study aims to characterize the variability of the in situ mechanical characteristics of the loess deposits from Hesbaye Region at the site scale and at the laboratory scale. Cone penetration tests (CPT), electrical resistivity tomographies (ERT) and drillings have been performed through a 10m thick loess layer in an investigation site located close to the CBR’s Romont quarry (Eben-Emael, Belgium) . Continuous undisturbed silt samples from drillings have been physically (granulometry, Atterberg limits, water content, organic matter content, carbonate content) and mechanically (oedometer test, triaxial test) characterized at the laboratory. Mechanical behavior and physical characteristics have underlined a series of layers with variable mechanical properties through depth. Some of these layers correlated with a detailed stratigraphy cross-section close to the investigation site could correspond to well-known paleosoils. [less ▲]

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See detailEstimation de tassements pour le site « Realex Tower »
Bertrand, François ULg; Collin, Frédéric ULg

Report (2015)

Rapport d'expertise de tassement sur base d'essais CPT et pressiométriques

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See detailThe influence of lithology on the mechanical strength and porosity of terra-cotta, the case study of Marrakech region (Morocco).
El Boudour El Idrissi, Hicham ULg; Daoudi, Lahcen; Collin, Frédéric ULg et al

Poster (2015, May 19)

The ceramic pastes in Marrakech region are prepared on the base of six types of raw materials of different lithologies. Various products are manufactured. The production consists of cooking utensils ... [more ▼]

The ceramic pastes in Marrakech region are prepared on the base of six types of raw materials of different lithologies. Various products are manufactured. The production consists of cooking utensils (based on schist, colluviums, quartzose sand and silt), decoration products (based on argillite, washing residues and soil), vases and gourds products (based on schist and soil), tiles (based on silt decantation) and traditional dishes (based on soil and argillite). In this study we elaborate bricks from the different raw material and we evaluate some of their physical properties after firing at 1050°C. In particular we measure the porosity to water and the mechanical strength of all the fired bricks. The aim is to compare the final product quality according to the origin (lithology) of the clayey raw material of the ceramic pastes. Based on our experiments, the bricks of the lower compressive strength (CS) and of the lower flexural strength (FS) are those based on sand (CS = 39 MPa; FS = 7 MPa), on silt decantation (CS = 25 to 39 MPa; FS = 10 to 18 MPa), and on schist and colluviums (CS = 20 to 51 MPa; FS = 6 to 17 MPa). Those of the highest values are based on argillites (CS = 33 to 102 MPa; FS = 13 to 28 MPa). The other pastes are characterized by intermediate values. The porosity ranges between 5 to 27%. The bricks based on silt decantation have the greatest values (20 to 27%), whereas those based on argillite have the lower values (5 to 10%). Those physical properties are, in most cases, in agreement with the requested values of the bricks industry. We conclude that such raw materials have high perspective to manufacture structural products of high performance in mechanical strength and thermal insulation. [less ▲]

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See detailSynthèse des données gétechniques nécessaires à l'étude de la stabilité de six terrils à risque en région liégeoise
Delvoie, Simon ULg; Collin, Frédéric ULg

Report (2015)

Dans le cadre d’un recensement des terrils situés en Région wallonne et pouvant présenter des risques de stabilité sur le court et le long terme, l’ISSeP a chargé le Laboratoire de Géotechnologies de ... [more ▼]

Dans le cadre d’un recensement des terrils situés en Région wallonne et pouvant présenter des risques de stabilité sur le court et le long terme, l’ISSeP a chargé le Laboratoire de Géotechnologies de l’Université de Liège, représenté par Ir. F. COLLIN et S. DELVOIE, de réaliser une étude géotechnique préliminaire. Les objectifs de ce travail sont tout d’abord de recenser les informations disponibles sur le sous-sol aux environs immédiats des terrils. Les données recueillies sont ensuite exploitées par des outils informatiques SIG et seront par la suite utilisées dans l’évaluation du risque d’instabilité, réalisée par l’ISSeP. Ce travail documentaire est également complété par une inspection sur le terrain de chaque terril étudié. Les terrils faisant partie de l’étude géotechnique sont repris dans la liste ci-dessous : - L60 – Petite Bacnure - L53 – Gosson 2 - L39 – Bonne Espérance et Bonne Fortune - L46 – Xhorre - L41 – Espérance 3 - L55 – Horloz [less ▲]

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See detailA doublescale model for hydromechanical coupling in clay rocks
van den Eijnden, Abraham Pieter ULg; Bésuelle, Pierre; Collin, Frédéric ULg et al

Conference (2015, March 26)

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

Conference (2015, March 26)

see attached abstract

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See detailModelling of large-scale in situ ventilation test in clayey rock
Pardoen, Benoît ULg; Collin, Frédéric ULg; Talandier, Jean

Poster (2015, March 23)

see attached file

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See detailA two-surface viscoplastic model for saturated clays
Hong, P.Y.; Cui, Y.J.; Pereira, J.M. et al

Poster (2015, March)

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See detailHydro-mechanical simulation in a deep excavation in Boom Clay
Hong, P.Y.; Cui, Y.J.; Pereira, J.M. et al

Poster (2015, March)

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See detailNumerical modeling of the long term behavior of Municipal Solid Waste in a landfill
Hubert, Julien ULg; Collin, Frédéric ULg

Scientific conference (2015, January 30)

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See detailUsing shear strain localisation to model the fracturing around gallery in unsaturated Callovo-Oxfordian claystone
Pardoen, Benoît ULg; Levasseur, Séverine ULg; Collin, Frédéric ULg

in Chau, Kam Tim; Zhao, Jidong (Eds.) Bifurcation and Degradation of Geomaterials in the New Millennium (2015, January 28)

Galleries drilling leads to damage propagation, fracturing and properties modifications in the surrounding medium. The prediction of the damaged zone behaviour is an important matter and needs to be ... [more ▼]

Galleries drilling leads to damage propagation, fracturing and properties modifications in the surrounding medium. The prediction of the damaged zone behaviour is an important matter and needs to be properly assessed. To do so the fractures can be modelled using shear strain localisation. The coupled local second gradient model is used under unsaturated conditions to correctly model the strain localisation behaviour. The permeability evolution and the rock desaturation due to air ventilation in galleries are considered. Finally, a hydro-mechanical modelling of a gallery excavation in Callovo-Oxfordian claystone is performed leading to a fairly good representation of the damaged zone. [less ▲]

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See detailModelling Hydromechanical Dilation Geomaterial—Cavitation and Localization
Sieffert, Y.; Buzzi, O.; Collin, Frédéric ULg et al

in Chau, Kam Tim; Zhao, Jidong (Eds.) Bifurcation and Degradation of Geomaterials in the New Millennium (2015, January)

This paper presents an extension of the local second gradient model to multiphasic materials (solid particles, air, water) and including the cavitation phenomenon. This new development was made in order ... [more ▼]

This paper presents an extension of the local second gradient model to multiphasic materials (solid particles, air, water) and including the cavitation phenomenon. This new development was made in order to model the response of saturated dilatant materials under deviatoric stress and undrained conditions and possibly, in future, the behaviour of unsaturated soils [less ▲]

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See detailUsing local second gradient model and shear strain localisation to model the excavation damaged zone in unsaturated claystone
Pardoen, Benoît ULg; Levasseur, Séverine ULg; Collin, Frédéric ULg

in Rock Mechanics & Rock Engineering (2015), 48(2), 691-714

The drilling of galleries induces damage propagation in the surrounding medium and creates, around them, the excavation damaged zone (EDZ). The prediction of the extension and fracture structure of this ... [more ▼]

The drilling of galleries induces damage propagation in the surrounding medium and creates, around them, the excavation damaged zone (EDZ). The prediction of the extension and fracture structure of this zone remains a major issue, especially in the context of underground nuclear waste storage. Experimental studies on geomaterials indicate that localised deformation in shear band mode usually appears prior to fractures. Thus, the excavation damaged zone can be modelled by considering the development of shear strain localisation bands. In the classical finite element framework, strain localisation suffers a mesh-dependency problem. Therefore, an enhanced model with a regularisation method is required to correctly model the strain localisation behaviour. Among the existing methods, we choose the coupled local second gradient model. We extend it to unsaturated conditions and we include the solid grain compressibility. Furthermore, air ventilation inside underground galleries engenders a rock– atmosphere interaction that could influence the damaged zone. This interaction has to be investigated in order to predict the damaged zone behaviour. Finally, a hydromechanical modelling of a gallery excavation in claystone is presented and leads to a fairly good representation of the EDZ. The main objectives of this study are to model the fractures by considering shear strain localisation bands, and to investigate if an isotropic model accurately reproduces the in situ measurements. The numerical results provide information about the damaged zone extension, structure and behaviour that are in very good agreement with in situ measurements and observations. For instance, the strain localisation bands that develop in chevron pattern during the excavation and rock desaturation, due to air ventilation, are observed close to the gallery. [less ▲]

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See detail3D zero-thickness coupled interface finite element: Formulation and application
Cerfontaine, Benjamin ULg; Dieudonné, Anne-Catherine ULg; Radu, Jean-Pol ULg et al

in Computers and Geotechnics (2015)

In many fields of geotechnical engineering, the modelling of interfaces requires special numerical tools. This paper presents the formulation of a 3D fully coupled hydro-mechanical finite element of ... [more ▼]

In many fields of geotechnical engineering, the modelling of interfaces requires special numerical tools. This paper presents the formulation of a 3D fully coupled hydro-mechanical finite element of interface. The element belongs to the zero-thickness family and the contact constraint is enforced by the penalty method. Fluid flow is discretised through a three-node scheme, discretising the inner flow by additional nodes. The element is able to reproduce the contact/loss of contact between two solids as well as shearing/sliding of the interface. Fluid flow through and across the interface can be modelled. Opening of a gap within the interface influences the longitudinal transmissivity as well as the storage of water inside the interface. Moreover the computation of an effective pressure within the interface, according to the Terzaghi’s principle creates an additional hydro-mechanical coupling. The uplifting simulation of a suction caisson embedded in a soil layer illustrates the main features of the element. Friction is progressively mobilised along the shaft of the caisson and sliding finally takes place. A gap is created below the top of the caisson and filled with water. It illustrates the storage capacity within the interface and the transversal flow. Longitudinal fluid flow is highlighted between the shaft of the caisson and the soil. The fluid flow depends on the opening of the gap and is related to the cubic law. [less ▲]

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See detailA FE² model for Hydro-mechanical coupling
van den Eijnden, Abraham Pieter ULg; Collin, Frédéric ULg; Bésuelle, Pierre et al

in Chau, Kam-Tim; Zhao, Jidong (Eds.) Bifurcation and Degradation of Geomaterials in the New Millenium (2015)

Detailed reference viewed: 7 (1 ULg)