Modeling of strain localization around the radioactive waste disposal galleries

in Coupled Phenomena in Environmental Geotechnics (2013)

On micromechanical damage modeling in geomechanics: influence of numerical integration scheme

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 ▲]

The role of the Excavated Damaged Zone in HGA field-scale Experiment Modelling

in FORGE Symposium (2013)

A micro–macro approach of permeability evolution in rocks excavation damaged zones

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 ▲]

Modelling the excavation damaged zone in Callovo-Oxfordian claystone with strain localization

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 ▲]

Numerical modelling of an in situ ventilation test in Callovo-Oxfordian claystone

Poster (2012, October)

Application of a new thermo-mechanical model for the study of the nuclear waste disposal in clay rocks

Poster (2012, October)

Modèles de comportement thermo-hydromécaniques inclus dans le code aux éléments finis LAGAMINE de l’Université de Liège

Report (2012)

Modelling the disturbed argillite - Strain localization

Scientific conference (2012, February 09)

The excavation process creates a damaged zone around the galleries composing underground structures. The prediction of the extension but especially of the fracturing structure in this zone remains an ... [more ▼]

The excavation process creates a damaged zone around the galleries composing underground structures. The prediction of the extension but especially of the fracturing structure in this zone remains an unresolved issue in the context of underground storage. Disturbed argillite and damage (fracturing) can be numerically modeled by the development of strain localization bands. Within the framework of classical finite elements, the strain localization depends on the mesh while the second gradient method overcomes this difficulty. This method is implemented in the finite element code Lagamine and is used to model biaxial compression tests performed in laboratory. [less ▲]

Field scale experiment modelling in Opalinus Clay: the HGA experiment

in Clays in Natural & Engineered Barriers for Radioactive Waste Confinement, 2012 (2012)