References of "Levasseur, Séverine"
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See detailModelling of the Excavation Damaged Zone in Opalinus Clay
Levasseur, Séverine ULg; Collin, Frédéric ULg; Charlier, Robert ULg

in Post-TIMODAZ International Workshop THM effects in clay host rocks for radioactive waste repositories (2012)

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See detailNumerical modelling in TIMODAZ: developments and achievements
Charlier, Robert ULg; Collin, Frédéric ULg; Levasseur, Séverine ULg

in Post-TIMODAZ International Workshop THM effects in clay host rocks for radioactive waste repositories (2012)

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See detailAnisotropic damage model for microcracked materials
Levasseur, Séverine ULg

Diverse speeche and writing (2012)

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See detailAnisotropic damage model with initial stresses for microcracked materials
Levasseur, Séverine ULg; Collin, Frédéric ULg; Charlier, Robert ULg et al

in Fifth International Conference on Advanced COmputational Methods in ENgineering (ACOMEN 2011) (2011)

In a recent study (Levasseur et al., 2010), we proposed a class of isotropic damage models which account for initial stresses. The present paper extends this approach to anisotropic damage due to growth ... [more ▼]

In a recent study (Levasseur et al., 2010), we proposed a class of isotropic damage models which account for initial stresses. The present paper extends this approach to anisotropic damage due to growth of an arbitrarily penny-shaped microcracks system. The basic principle of the upscaling technique in the presence of initial stress is first recalled. Then, we derive a closed-form expression of the elastic energy potential corresponding to a system of arbitrarily oriented microcracks. Thanks to the investigation of the influence of initial stresses on the material response under non monotonous loading paths, it is shown how the coupling between initial stresses and damage is strongly dependent of the microcracks density and orientation. In case of a particular distribution of microcracks orientation, described by a second order damage tensor, this model corresponds to a generalization of the macroscopic damage model of Halm and Dragon (1996), for which a physically-based interpretation can be proposed. [less ▲]

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See detailModélisation par changement d’échelle de l’endommagement et des évolutions de perméabilité dans l’argilite
Levasseur, Séverine ULg; Collin, Frédéric ULg; Charlier, Robert ULg et al

in 20ème Congrès Français de Mécanique (2011)

Le creusement d’excavations souterraines dans une roche est à l’origine de la formation d’une zone endommagée, où des microfissures se développent et perturbent fortement les propriétés de transport du ... [more ▼]

Le creusement d’excavations souterraines dans une roche est à l’origine de la formation d’une zone endommagée, où des microfissures se développent et perturbent fortement les propriétés de transport du matériau. L’objectif de cette étude est de représenter ces phénomènes hydromécaniques par une approche micromécanique d’endommagement, couplée aux évolutions de perméabilité, en présence de contraintes initiales, puis d’en discuter les avantages et les inconvénients sur la base d’une simulation du creusement d’un tunnel dans l’argile à Opalinus relatif à l’expérience SELFRAC. [less ▲]

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See detailTunnel excavation modeling with micromechanical approaches
Levasseur, Séverine ULg; Collin, Frédéric ULg; Charlier, Robert ULg et al

in IWBDG (2011)

A zone with significant irreversible deformations and significant changes in flow and transport properties is expected to be formed around underground excavation in the deep geological layers considered for ... [more ▼]

A zone with significant irreversible deformations and significant changes in flow and transport properties is expected to be formed around underground excavation in the deep geological layers considered for the high level radioactive waste disposal. The present study concerns the modeling of this phenomena by a micromechanical damage model, based on a Mori-Tanaka homogenization on a cracked media. This anisotropic model is derived from Eshelby homogenized scheme, on which a coupling between damage and friction is taking into account on cracks. Compared to elastoplastic model on tunnel drilling modeling, micromechanical modeling seems very promising: both approaches provide similar EDZ sizes and shapes even if they do not have the same effects on perturbed mechanical behavior; micromechanical model also overcomes the elastoplastic one by a realistic characterization of crack processes. [less ▲]

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See detailMulti-scale modelling of permeability evolution in the excavation damaged zone around tunnels
Levasseur, Séverine ULg; Collin, Frédéric ULg; Charlier, Robert ULg et al

in PROCEEDINGS OF THE 2nd INTERNATIONAL SYMPOSIUM ON COMPUTATIONAL GEOMECHANICS (COMGEO I ) (2011)

A zone with significant irreversible deformations and significant changes in flow and transport properties is expected to be formed in indurated clay around underground excavations. The stress perturbation ... [more ▼]

A zone with significant irreversible deformations and significant changes in flow and transport properties is expected to be formed in indurated clay around underground excavations. The stress perturbation around the excavation could lead to a significant increase of the permeability, related to diffuse and/or localized crack propagation in the material. The main objective of the study is to model these processes at large scale with a micromechanical damage approach, based on the Ponte-Castaneda and Willis approximation (PCW) in the presence of initial stress, in order to assess the crack impacts on the performance of radioactive waste geological repositories. Combined with this model, permeability tensor is described as a function of micromechanical damage that is generated during the excavation. Advantages and drawbacks of this approach are described thanks to the results on Opalinus Clay and of the Selfrac long term dilatometer experiment. [less ▲]

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See detailA two scale anisotropic damage model accounting for initial stresses in microcracked materials
Levasseur, Séverine ULg; Collin, Frédéric ULg; Charlier, Robert ULg et al

in Engineering Fracture Mechanics (2011), 78

In a recent study [15], we proposed a class of isotropic damage models which account for initial stresses. The present paper extends this approach to anisotropic damage due to growth of an arbitrarily ... [more ▼]

In a recent study [15], we proposed a class of isotropic damage models which account for initial stresses. The present paper extends this approach to anisotropic damage due to growth of an arbitrarily penny-shaped microcracks system. The basic principle of the upscaling technique in the presence of initial stress is first recalled. Then, we derive a closed-form expression of the elastic energy potential corresponding to a system of arbitrarily oriented microcracks. It is shown that the coupling between initial stresses and damage is strongly dependent of the microcracks density and orientation. Predictions of the proposed model are illustrated through the investigation of the influence of initial stresses on the material response under non monotonous loading paths. Finally, by considering a particular distribution ofmicrocracks orientation, described by a second order damage tensor, it is shown that the model is a generalization of the macroscopic damage model of Halm and Dragon [9], for which a physically-based interpretation is then proposed. [less ▲]

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See detailApplications to Geotechnical Problems of the Micromechanical Modeling of Damage
Levasseur, Séverine ULg; Collin, Frédéric ULg; Charlier, Robert ULg et al

in Multiscale & Multiphysics Processes in Geomechanics (2010)

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See detailEDZ and Permeability in Clayey Rocks
Levasseur, Séverine ULg; Bésuelle, Pierre; Collin, Frédéric ULg et al

in Clays in Natural and Engineered Barriers for Radioactive Waste Confinement 2010 (2010)

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See detailOn the micro-scale modelling by homogenization schemes in geomechanics
Levasseur, Séverine ULg; Collin, Frédéric ULg; Charlier, Robert ULg et al

in USNCTAM 2010 (2010)

The mechanical behaviors of geomaterials are significantly affected by the presence of voids or cracks-like defects. The modeling of such behavior is classically performed by considering purely ... [more ▼]

The mechanical behaviors of geomaterials are significantly affected by the presence of voids or cracks-like defects. The modeling of such behavior is classically performed by considering purely macroscopic or micromechanically-based damage models. In the perspective of applications in civil engineering or in geomechanics, we propose in this paper to evaluate a homogenization approach, based on Mori-Tanaka scheme, applied to micro-cracked materials. In order to provide an appropriate interpretation of the nonlinear behavior at macro-scale, the crack-induced damage is coupled to friction phenomena on closed cracks lips. The predictions of the coupled model are first analyzed on laboratory tests performed on Callovo-Oxfordian Clay. Then, they are extended to a numerical analysis of excavation damaged zones around tunnels [less ▲]

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See detailTIMODAZ report: Deliverable D13 – Simulation of lab and in situ tests
Charlier, Robert ULg; Chambon, R; Collin, Frédéric ULg et al

Report (2010)

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See detailTIMODAZ report: Deliverable D10 - Constitutive models development
Arson, C; Charlier, Robert ULg; Chambon, R et al

Report (2010)

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See detailComparison of two inverse analysis techniques for learning deep excavation response
Hashash, Youssef; Levasseur, Séverine ULg; Osouli, Abdolreza et al

in Computers & Geotechnics (2010), 37

Performance observation is a necessary part of the design and construction process in geotechnical engineering. For deep urban excavations, empirical and numerical methods are used to predict potential ... [more ▼]

Performance observation is a necessary part of the design and construction process in geotechnical engineering. For deep urban excavations, empirical and numerical methods are used to predict potential deformations and their impacts on surrounding structures. Two inverse analysis approaches are described and compared for an excavation project in downtown Chicago. The first approach is a parameter optimization approach based on genetic algorithm (GA). GA is a stochastic global search technique for optimizing an objective function with linear or non-linear constraints. The second approach, self-learning simulations (SelfSim), is an inverse analysis technique that combines finite element method, continuously evolving material models, and field measurements. The optimization based on genetic algorithm approach identifies material properties of an existing soil model, and SelfSim approach extracts the underlying soil behavior unconstrained by a specific assumption on soil constitutive behavior. The two inverse analysis approaches capture well lateral wall deflections and maximum surface settlements. The GA optimization approach tends to overpredict surface settlements at some distance from the excavation as it is constrained by a specific form of the material constitutive model (i.e. hardening soil model); while the surface settlements computed using SelfSim approach match the observed ones due to its ability to learn small strain non-linearity of soil implied in the measured settlements. [less ▲]

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See detailDamage modelling in geotechnics: micromechanical approaches
Levasseur, Séverine ULg; Collin, Frédéric ULg; Charlier, Robert ULg et al

in Zhao, Jian; Labiouse, Vincent; Dudt, Jean-Paul (Eds.) et al EUROCK2010: Rock Mechanics in Civil and Environmental Engineering (2010)

The mechanical behaviours of geomaterials are significantly affected by the presence of voids or cracks-like defects. The modelling of such behaviour is classically performed by considering purely ... [more ▼]

The mechanical behaviours of geomaterials are significantly affected by the presence of voids or cracks-like defects. The modelling of such behaviour is classically performed by considering purely macroscopic or micromechanically-based damage models. In the perspective of applications in civil engineering or in geomechanics, we propose in this paper to evaluate a homogenization approach, based on Mori-Tanaka scheme, applied to microcracked materials. In order to provide an appropriate interpretation of the nonlinear behaviour at macro-scale, the crack-induced damage is coupled to friction phenomena on closed cracks lips. The predictions of the coupled model are first analysed on laboratory tests performed on Callovo-Oxfordian Clay. Then, they are extended to a numerical analysis of excavation damaged zones around tunnels. [less ▲]

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See detailStatistical inverse analysis based on genetic algorithm and principal component analysis: Applications to excavation problems and pressuremeter tests
Levasseur, Séverine ULg; Malécot, Yann; Boulon, Marc et al

in International Journal for Numerical and Analytical Methods in Geomechanics (2010), 34(5), 471-491

This study concerns the identification of constitutive models from geotechnical measurements by inverse analysis. Soil parameters are identified from measured horizontal displacements of sheet pile walls ... [more ▼]

This study concerns the identification of constitutive models from geotechnical measurements by inverse analysis. Soil parameters are identified from measured horizontal displacements of sheet pile walls and from a measured pressuremeter curve. An optimization method based on a genetic algorithm and a principal component analysis, developed and tested on synthetic data in a previous paper, is applied. These applications show that the conclusions deduced from synthetic problems can be extrapolated to real problems. The genetic algorithm is a robust optimization method which is able to deal with the non-uniqueness of the solution in identifying a set of solutions for a given uncertainty on the measurements. This set is then characterized by a principal component analysis (PCA) which gives a fi rst order approximation of the solution as an ellipsoid. When the solution set is not too curved in the research space, this ellipsoid characterizes the soil properties considering the measured data and the tolerate margins for the response of the numerical model. Besides, optimizations from di fferent measurements provide solution sets with a common area in the research space. This intersection gives a more relevant and accurate identification of parameters. Finally, we show that these identified parameters permit to reproduce geotechnical measurements not used in the identification process. [less ▲]

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See detailHydro-mechanical modelling of the Excavation Damaged Zone around an underground excavation at Mont Terri Rock Laboratory
Levasseur, Séverine ULg; Charlier, Robert ULg; Frieg, Bernd et al

in International Journal of Rock Mechanics & Mining Sciences (2010), 47(3), 414-425

A zone with significant irreversible deformations and significant changes in flow and transport properties is expected to be formed in indurated clay around underground excavations. The stress ... [more ▼]

A zone with significant irreversible deformations and significant changes in flow and transport properties is expected to be formed in indurated clay around underground excavations. The stress perturbation around the excavation could lead to a significant increase of the permeability, related to diffuse and/or localized crack propagation in the material. The main objective of the study is to model these processes at large scale in order to assess their impacts on the performance of radioactive waste geological repositories. This paper concerns more particularly the hydro-mechanical modelling of a long term dilatometer experiment performed in Mont Terri Rock Laboratory in Switzerland within the Selfrac Project. The proposed model defines the permeability as a function of the aperture of the cracks that are generated during the excavation. With this model, the permeability tensor becomes anisotropic. Advantages and drawbacks of this approach are described thanks to the results of the Selfrac long term dilatometer experiment. [less ▲]

Detailed reference viewed: 93 (15 ULg)