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Modélisation des réactions de gonflement interne des bétons avec prise en compte des couplages poro-mécaniques et chimiques

Abstract : Internal swelling reactions (ISR) damage the concrete of structures such as dams. Electricité De France (EDF) must ensure the safety of the people and goods located below the dam. This work aims to improve the modeling of the physical phenomena related to these damages, especially the interaction between the swelling product and the solid skeleton. The intraporous stress generated by the product pressure can create cracking, which, in the proposed model, can occur at two scales: - At a microscopic scale, the swelling product fills the gaps around the reaction site, which induces cracking and a decrease of the materials' characteristics (tensile and compression strengths, Young's modulus). Numerically, an anisotropic plastic criteria and a hardening law allow modelling this phenomenon. - At a macroscopic level, swelling gradients can develop inside concrete structures whose stress states and climatic conditions (humidity and temperature) are not homogeneous. A localized cracking can begin. It is a source of structure dislocation risks and stress concentrations in structural reinforcement. It may ease the way in for outside aggressive agents and water, an essential component for these reactions. Hydro-poro-mechanical couplings need to be taken into account when simulating these phenomena. The cracking is modelled by a Rankine plastic criterion whose dissipated energy is regularized by the Hillerborg's method. After presenting the model, several stress states and environmental conditions are applied to the model in order to validate it on: - samples under multi-axial stresses and restraints, - plain and reinforced beams submitted to moisture gradients in laboratory, - 1950s dams in real conditions. The results of the model make it possible to reproduce the displacements, the stresses and residual strength of these structures after aging. For the beams submitted to alkali aggregate reaction, the numerical results show a relevant prediction of the stress induced by reinforcement, confirmed by the failure behaviour. Nevertheless, the model encounters calibration difficulties for beams affected by delayed ettringite formation. They come from large swelling amplitude and diffusion-cracking coupling which are inherent to these structure behaviours. This model is a tool for concrete structure requalification in order to ensure their safety. It can also be a basis for diverse rehabilitations and reinforcement works simulation.
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https://tel.archives-ouvertes.fr/tel-01845620
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Submitted on : Friday, July 20, 2018 - 3:09:05 PM
Last modification on : Saturday, August 15, 2020 - 3:54:10 AM
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2017TOU30138b.pdf
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  • HAL Id : tel-01845620, version 1

Citation

Pierre Morenon. Modélisation des réactions de gonflement interne des bétons avec prise en compte des couplages poro-mécaniques et chimiques. Matériaux composites et construction. Université Paul Sabatier - Toulouse III, 2017. Français. ⟨NNT : 2017TOU30138⟩. ⟨tel-01845620⟩

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