Modélisations couplées thermo-hydro-mécaniques en milieux poreux partiellement saturés : solutions linéaires et non linéaires

Abstract : On the basis of the princip le that an artificial material like a concrete, or well a natural material such as a clay, can be regarded as polyphase porous materials, in which occur interactions between the phases solid, liquid and possibly gas, the differential equations governing the thermo-hydro-mechanical coupled behavior were established in the formalism defined by Coussy (1995), by a rigorous step being based on thermodynamic arguments. For certain problems, in the case of one-dimensional geometry, a linearized approach can be considered. The diagram of resolution for a linear study is of semi-explicit type: the existing techniques were wide to be able to solve coupled problems and two numerical methods of inversion of the Laplace transforms were more particularly studied and validated (Stehfest, 1970; Piessens et al., 1983). The interest of the semi explicit approaches is double since they make it possible to validate computer codes and they are also very useful to make sensitivity analyses thanks to their calculation speed. In the other band, a finite elements computer code, PARSAT, was developed in LAEGO to solve the system of equations which is generally non-linear. This theoretical framework and these tools were then made profitable to model three applications being of strong industrial interest, in relation to EDF, the French electricity company. A first study relates to the storage of the high activity radioactive waste with the concept of Clay Barrier (CB), and is interested in the kinetics of ressaturation of the CB. This clay layer is initially not saturated and is hydrated gradually in contact with the surrounding rock mass to form a barrier around the waste containers. The second application is based on the phenomenon of desiccation shrinkage. After a general study on ideal concrete structures, an analysis of distribution in a clay gallery is proposed to explain the link between the dessaturation of the rock mass and the appearance of a cracking in the wall of the gallery, as it could be observed on the site of Tournemire. Lastly, a third study relates to the problem of insulating building wall. A wall is modelled like a unit made up of several layers (plaster, brick-masonry, polystyrene, rendering) and two different layouts are studied (internal or external insulation). The strong external climatic variations induce the appearance of tensile stresses in the model which can be at the origin of decohesion between materials.
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Gilles Thouvenon. Modélisations couplées thermo-hydro-mécaniques en milieux poreux partiellement saturés : solutions linéaires et non linéaires. Autre. Institut National Polytechnique de Lorraine, 1999. Français. ⟨NNT : 1999INPL051N⟩. ⟨tel-01749931⟩

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