References of "Collin, Frédéric"
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See detailA fully coupled hydro-mechanical model for the modeling of coalbed methane recovery
Bertrand, François ULg; Cerfontaine, Benjamin ULg; Collin, Frédéric ULg

in Natural Gas science and Engineering (2018)

Most coal seams hold important quantities of methane which is recognized as a valuable energy resource. Coal reservoir is considered not conventional because methane is held adsorbed on the coal surface ... [more ▼]

Most coal seams hold important quantities of methane which is recognized as a valuable energy resource. Coal reservoir is considered not conventional because methane is held adsorbed on the coal surface. Coal is naturally fractured, it is a dual-porosity system made of matrix blocks and cleats (i.e fractures). In general, cleats are initially water saturated with the hydrostatic pressure maintaining the gas adsorbed in the coal matrix. Production of coalbed methane (CBM) first requires the mobilization of water in the cleats to reduce the reservoir pressure. Changes of coal properties during methane production are a critical issue in coalbed methane recovery. Indeed, any change of the cleat network will likely translate into modifications of the reservoir permeability. This work consists in the formulation of a consistent hydro-mechanical model for the CBM production modeling. Due to the particular structure of coal, the model is based on a dual-continuum approach to enrich the macroscale with microscale considerations. Shape factors are employed to take into account the geometry of the matrix blocks in the mass exchange between matrix and fractures. The hydro-mechanical model is fully coupled. For example, it captures the sorption-induced volumetric strain or the dependence of permeability on fracture aperture, which evolves with the stress state. The model is implemented in the finite element code Lagamine and is used for the modeling of one production well. A synthetic reservoir and then a real production case are considered. To date, attention has focused on a series of parametric analyses that can highlight the influence of the production scenario or key parameters related to the reservoir. [less ▲]

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See detailOn the modelling of coupled hydro-mechanical behaviour of interfaces for offshore foundations
Cerfontaine, Benjamin ULg; Collin, Frédéric ULg

in Rasmussen, Amalie (Ed.) Marine Engineering: Emerging Developments and Global Challenges (2017)

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See detailHydro-mechanical modelling of a coalbed methane production well via a dual-porosity approach
Bertrand, François ULg; Buzzi, Olivier; Collin, Frédéric ULg

in Book of Abstracts: 6th International Conference on Coupled THMC Processes in Geosystems (2017, July)

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See detailAnisotropic modelling of Opalinus Clay behaviour: from triaxial tests to gallery excavation application
Bertrand, François ULg; Collin, Frédéric ULg

in Journal of Rock-Mechanics and Geotechnical Engineering (2017)

Deep repository in geological formations is the preferential solution considered by many countries to manage high-level nuclear wastes. In Switzerland, the Opalinus Clay is a candidate host rock. In this ... [more ▼]

Deep repository in geological formations is the preferential solution considered by many countries to manage high-level nuclear wastes. In Switzerland, the Opalinus Clay is a candidate host rock. In this context, in situ and laboratory tests are conducted on Opalinus Clay to demonstrate the feasibility of deep disposal in this argillaceous formation. This paper presents a constitutive model able to fit the experimental data obtained from some triaxial tests conducted by Jahns [1] on cores from bore hole Schlattingen SLA- 1. The elasto-plastic behaviour of Opalinus Clay is reproduced thanks to a Drucker-Prager model, taking into account the anisotropy behaviour of this sedimentary rock. The objective is to employ a single set of parameters representative of the material. In a second version of the model, the stress-dependency of the elastic properties and damage are taken into account. Finally, the parameters calibrated with experimental tests are used to simulate the excavation of a gallery with a second gradient approach. [less ▲]

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See detailValidation of a new elastoplastic constitutive model dedicated to the cyclic behaviour of brittle rock materials
Cerfontaine, Benjamin ULg; Charlier, Robert ULg; Collin, Frédéric ULg et al

in Rock Mechanics & Rock Engineering (2017)

Old mines or caverns may be used as reservoirs for fuel/gas storage or in the context of large-scale energy storage. In the first case, oil or gas is stored on annual basis. In the second case pressure ... [more ▼]

Old mines or caverns may be used as reservoirs for fuel/gas storage or in the context of large-scale energy storage. In the first case, oil or gas is stored on annual basis. In the second case pressure due to water or compressed air varies on a daily basis or even faster. In both cases a cyclic loading on the cavern’s/mine’s walls must be considered for the design. The complexity of rockwork geometries or coupling with water flow requires finite element modelling and then a suitable constitutive law for the rock behaviour modelling. This paper presents and validates the formulation of a new constitutive law able to represent the inherently cyclic behaviour of rocks at low confinement. The main features of the behaviour evidenced by experiments in the literature depict a progressive degradation and strain of the material with the number of cycles. A constitutive law based on a boundary surface concept is developed. It represents the brittle failure of the material as well as its progressive degradation. Kinematic hardening of the yield surface allows the modelling of cycles. Isotropic softening on the cohesion variable leads to the progressive degradation of the rock strength. A limit surface is introduced and has a lower opening than the bounding surface. This surface describes the peak strength of the material andallows the modelling of a brittle behaviour. In addition a fatigue limit is introduced such that no cohesion degradation occurs if the stress state lies inside this surface. The model is validated against three different rock materials and types of experiments. Parameters of the constitutive laws are calibrated against uniaxial tests on Lorano marble, triaxial test on a sandstone and damage-controlled test on Lac du Bonnet granite. The model is shown to reproduce correctly experimental results, especially the evolution of strain with number of cycles. [less ▲]

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See detailLoi de comportement pour les argiles naturelles
Ahayan, Sanae ULg; Cerfontaine, Benjamin ULg; Collin, Frédéric ULg

Scientific conference (2017, May 23)

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See detailHydro-mechanical modelling of coalbed methane recovery
Bertrand, François ULg; Buzzi, Olivier; Cerfontaine, Benjamin ULg et al

Diverse speeche and writing (2017)

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See detailModeling the strain localization around an underground gallery with a hydro-mechanical double scale model; effect of anisotropy
van den Eijnden, AP; Bésuelle, Pierre; Collin, Frédéric ULg et al

in Computers and Geotechnics (2017), 85

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See detailOn the Variable Dilatancy Angle in Rocks Around Underground Galleries
Salehnia, Fatemeh ULg; Collin, Frédéric ULg; Charlier, Robert ULg

in Rock Mechanics & Rock Engineering (2016)

Correct estimation of the dilatant behavior of a rock has an essential role in a realistic numerical simulation of the fracturing threshold during the rock deformation process and its post-failure ... [more ▼]

Correct estimation of the dilatant behavior of a rock has an essential role in a realistic numerical simulation of the fracturing threshold during the rock deformation process and its post-failure response, based on experimental and field observations. This importance has been poorly treated in most of the numerical analyses dealing with the rock engineering common problems such as deep excavations. The dilatancy angle as a commonly used parameter for describing the dilatation response of a rock is mostly simplified to be a constant value. Contrarily, a literature review declares the inadequacy of this approach in those rock mechanics applications. In the present paper, a new formula for considering the variable dilatancy angle is presented which relates this parameter to the plastic shear strain in the course of a loading procedure. It is aimed at characterizing an evolution of the dilatant or contracting volumetric response of a rock as well as giving the possibility to simulate a dilatant/contracting transitional behavior. The model is applied to simulate the development of strain localization, in shear band mode, within the inevitable excavation damaged zone created around an underground opening in rock. It is illustrated that using the model of variable dilatancy angle in a deep excavation modeling could help to better reproduce the fractures development around the opening in the course of tunneling. [less ▲]

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See detailNumerical modeling of coupled thermal-hydro-mechanical behavior of GMZ bentonite in the China-Mock-up test
Zhao, Jingbo; Chen, Liang; Collin, Frédéric ULg et al

in Engineering Geology (2016), 214

Gaomiaozi (GMZ) bentonite is currently considered as themost suitable buffermaterial for high-level radioactive waste geological repository in China. To investigate the long-term performance of GMZ ... [more ▼]

Gaomiaozi (GMZ) bentonite is currently considered as themost suitable buffermaterial for high-level radioactive waste geological repository in China. To investigate the long-term performance of GMZ bentonite under repository conditions, a large scale mock-up test has been carried out since 2011. In the test, a hydration systemand an electrical heater were employed to simulate the Thermal-Hydro-Mechanical (THM) coupled conditions near a repository. In this work, a numerical study is performed to reproduce the experimental data obtained in the first three years of the China-Mock-up experiment. The principle THM characteristics and parameters of the bentonite are presented. On this basis, a THM coupled constitutive model is introduced. With the proposed model, numerical simulations of the China-Mock-up test are carried out using LAGAMINE. The numerical data of temperature, relative humidity, and swelling pressure of the GMZ compacted bentonite are compared with the experimental ones.We discuss the effect of the balance between the drying effect and water penetration process on the THM behavior of the GMZ bentonite. The good agreement between the predicted and experimental results suggests that the proposed model can reproduce the fundamental behavior of GMZ compacted bentonite under coupled THM conditions. [less ▲]

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See detailEffect of rotational hardening rule on the behavior of clayey soils
Ahayan, Sanae ULg; Kotronis, Panagiotis; Collin, Frédéric ULg et al

Scientific conference (2016, October 26)

Induced anisotropy is a constitutive feature of clays that can be numerically introduced through a proper "Rotational Hardening Rule" allowing the rotation of the yield and the potential plastic surfaces ... [more ▼]

Induced anisotropy is a constitutive feature of clays that can be numerically introduced through a proper "Rotational Hardening Rule" allowing the rotation of the yield and the potential plastic surfaces in the stress space. In this presentation, rotational hardening rule of yield surface for clays are first reviewed. Then, two typical rotational hardening rules are selected and compared through simulating drained triaxial tests of two Finnish clays. Furthermore, finite element simulations of a strip rigid footing considering different rotational hardening rules together with the case of isotropic yield surface without rotation are carried out in order to study the consequences of the isotropy assumption and the influence of the rotational hardening rule on the behavior of shallow foundation. [less ▲]

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See detailBounding surface plasticity model for natural clays
Ahayan, Sanae ULg; Yin, Zhen-Yu; Kotronis, Panagiotis et al

Conference (2016, October 26)

Natural soft clay exhibits a considerable degree of anisotropy as a result of its past sedimentation and consolidation history. It also tends to have significant inter-particle bonding, which affects its ... [more ▼]

Natural soft clay exhibits a considerable degree of anisotropy as a result of its past sedimentation and consolidation history. It also tends to have significant inter-particle bonding, which affects its mechanical behavior. The natural structure of in-situ soils makes their behavior different from that of a reconstituted material. In fact, most clays lose a proportion of their strength when remoulded. Various authors proposed anisotropic elastoplastic soil models allowing the yield surface to rotate with the stress history. These models have a “rotational hardening law" which relates the change of the inclination of the yield surface to the current soil state and to the increments of the plastic volumetric and/or shear strain, [Sekiguchi and Otha (1977)], [Hashiguchi and Chen (1998)], [Wheeller et al (2003)]… Other authors combine the plastic anisotropy with destructuration effects observed in soft sensitive soils by assuming that the size and /or the position of the center of the yield surface depends on the amount of the structural soil degradation. These models use an additional isotropic hardening law that relates the size and/or the position of the yield surface of the intact sample to that of the reconstituted one [Nova et al (2003)]. The previous models provide little or no flexibility when it comes to describe the change of the plastic modulus with the loading direction as they are unable to produce a smooth degradation of the stiffness, being single yield surface models. A way to improve this behavior is to introduce the “bounding surface plasticity” theory, initially developed by Dafalias [Dafalias and Herrmann 1986]. Unlike a single yield surface model, the bounding surface theory allows a smooth transition of stresses within and on the bounding surface. The mean feature of this concept is that the actual stress is mapped to the imaginary stress on the bounding surface. The distance between the real and imaginary stress, which is called the “ function distance ”, is used to specify the plastic modulus. This work presents a bounding surface plasticity model for natural and structured clays based on the critical state theory. A novel rotational hardening rule for clays is presented, and a hardening function distance is introduced to describe the evolution of the bounding surface. Validation of the model is provided by drained and undrained tests of Scottish and Finnish intact and reconstituted clays [Kastunnen 2008]. Finally, finite element simulations of a foundation considering the formulated constitutive law are presented. [less ▲]

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See detailRetour en grâce du grisou
Bertrand, François ULg; Charlier, Robert ULg; Collin, Frédéric ULg

Diverse speeche and writing (2016)

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See detailDetailed characterization of the Late Pleistocene loess sequence stratigraphy of Remicourt (Hesbaye region, Belgium) with cone penetration tests
Delvoie, Simon ULg; Boulvain, Frédéric ULg; Charlier, Robert ULg et al

in Geologica Belgica (2016), 19(3-4), 281-289

Cone penetration tests (CPT) and drilling results are used to characterize the Middle Belgium loess sequence. A two scale study has been realized in the Hesbaye region (Belgium). The study on a regional ... [more ▼]

Cone penetration tests (CPT) and drilling results are used to characterize the Middle Belgium loess sequence. A two scale study has been realized in the Hesbaye region (Belgium). The study on a regional scale was performed along a 18 km long section of the high-speed railway Liège-Brussels. About 230 tests were compiled. Results show the loess thickness is very variable and can locally reach 20 m. Tertiary deposits become continuous and they rapidly thicken from Waremme to the West. The lower surface of the Tertiary deposits is characterized by a 0.3% apparent dipping to the NW. The dipping likely results from the Ardenne Massif uplift. The local scale study focuses on the site of Remicourt located along the high-speed railway. 24 CPT tests have been carried out very close to a series of archaeological trenches. The analysis shows penetrometers are able to define some stratigraphic markers within the loess layer. The most identifiable marker is stratigraphically located around the transition between the Humiferous Complex of Remicourt and the Rocourt Pedocomplex. The lens-shape of the loess ridge is also confirmed by the penetrometers’ interpretation. Furthermore, the 3D morphology of each stratigraphic marker can be estimated. These results offer interesting perspectives for the investigation of the loess sequence related to archaeological applications. [less ▲]

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See detailSynthèse des données gétechniques nécessaires à l'étude de la stabilité de cinq terrils à risque en région wallonne - phase2
Delvoie, Simon ULg; Collin, Frédéric ULg

Report (2016)

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 : - Argenteau Ancien et Argenteau Nouveau – OBID 578-579 – L6 et L7 - Saint-Placide – OBID 343 – B60 - 14-17 et Siège social – OBID 5151 – B80-1 - Héribus – OBID 557 – B88-1 - Crachet 7/12 – OBID 286 – B111 [less ▲]

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See detailL'effet de l'écrouissage rotationnel sur le comportement des sols argileux
Ahayan, Sanae ULg; Yin, Zhen-Yu; Kotronis, Panagiotis et al

Conference (2016, May 25)

Induced anisotropy is a constitutive feature of clays that can be introduced through a proper "Rotational hardening law" allowing the rotation of the yield and the potential plastic surfaces in the stress ... [more ▼]

Induced anisotropy is a constitutive feature of clays that can be introduced through a proper "Rotational hardening law" allowing the rotation of the yield and the potential plastic surfaces in the stress space. Two rotational hardening laws are studied in this paper. Validation is provided using the results of a drained triaxial test of a Finnish clay. Finite Elements simulations of a circular rigid footing considering an isotropic and anisotropic constitutive laws are presented. The objective is firstly to identify the influence of the isotropy assumption in geotechnical design and secondly to study the effect of different hardening laws on the foundation behavior. [less ▲]

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