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Etude théorique et numérique du comportement poro-plastique endommageable non saturé des géomatériaux : application au stockage de déchets radioactifs

Abstract : This thesis aims to study the damageable hydromechanical behavior of unsaturated geomaterials. More precisely, the research is applied to study the behavior of underground galleries of radioactive waste disposals in deep geological formations. Firstly, after summarizing the main features of the hydro-mechanical behavior of geomaterials, emphasizing the effect of suction and damage, a new model PPE-N coupling hydromechanical interactions with plasticity and isotropic damage is presented. Established in the framework of thermodynamics of porous media, it is based on the concept of the so called plastic effective stress and equivalent pore pressure. Assuming a bimodal pore size distribution for cracked porous media and using the concept of bundle cylindrical capillaries, damage effects on hydraulic behaviour (water retention curve and hydraulic conductivity) is modelled using phenomenological functions. The accountance of the contributions to the interfacial energy from the mechanical internations between solid and fluid phases (via theequivalent pore pressure) as well as the physico-chemical mechanism of water retention (via the water retention function) enables this model to describe in apertinent manner bilateral couplings between them.Secondly, this constitutive model is applied to Callovo- Oxfordian argillite, which is the potential host rock for the French nuclear waste disposal, and then to study the evolution of the hydromechanical responses of an underground gallery according to its simplified life cycle. The model is first validated against a range of mechanical and hydraulic laboratory tests, considering "homogeneous" samples. The analytical approach is then used to provide an exact reference solution of this problem in the limiting case of a saturated poro-viscoplastic host rock. This solution allows to better understand the effect of creep on the behavior of the gallery and also to test the precision of other complex numerical solutions . Finally, the numerical approach using finite elemnts is used to implement the new model EPP-NS in a computer code originally developed in LGCB (Laboratoire Genie Civil et Batiment). Its validity is partly checked by examining the poroelastic behavior of an unlined tunnel where quasi-analytical solutions have been developed. Parametric studies in the generalcase of a lined tunnel demonstrate the consistency of the model and highlight the influence of desaturation on the behavior of the gallery.
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  • HAL Id : tel-01631785, version 1

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Tuan Anh Bui. Etude théorique et numérique du comportement poro-plastique endommageable non saturé des géomatériaux : application au stockage de déchets radioactifs. Mécanique des matériaux [physics.class-ph]. École Nationale des Travaux Publics de l'État [ENTPE], 2014. Français. ⟨NNT : 2014ENTP0015⟩. ⟨tel-01631785⟩

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