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Theses

Influence des solutions aqueuses sur le comportement mécanique des roches argileuses

Abstract : The hydration of the shale with an aqueous solution induces a swelling deformation which plays an
important role in the behaviour of the structures excavated in this type of grounds. This deformation
is marked by a three-dimensional and anisotropic character and involves several mechanisms
like adsorption, osmosis or capillarity.
Several researches were dedicated to swelling and were often much debated due to the complexity of
the implied phenomena. The goal of this thesis is therefore to contribute to a better understanding
of shale swelling when the rock is confined and hydrated with an aqueous solution. The main part
of the work accomplished was related to the Lorraine shale and to the Tournemire shale.
To characterize swelling and to identify the main governing parameters, it was necessary to start the
issue with an experimental approach. Many apparatus were then developed to carry out tests under
various conditions of swelling. In order to facilitate the interpretation of the tests and thereafter
the modelling of the behaviour, the experimental procedure adopted consisted of studying first the
mechanical aspect and then the chemical aspect of swelling.
In the mechanical part, swelling was studied by imposing on the sample a mechanical loading while
maintaining during the tests the same aqueous solution. The principal parameters which were studied
are the effect of the lateral conditions on axial swelling (impeded strain or constant stress) as
well as the influence of the axial stress on radial swelling. The anisotropy of swelling was studied
by carrying out, for different orientations of the sample, tests of free swelling, impeded swelling and
uniaxial swelling. These various mechanical tests allowed to study the three-dimensional anisotropic
swelling in all the conditions and to select the most appropriate test to be used in the second phase
of the research.
The precise analysis performed to explain the mechanisms behind the swelling of an argillaceous rock
when it is in contact of water showed that the mechanical response is ruled mainly by electrochemical
phenomena which operate between the solution elements and the clay layers. This important
result oriented the research to develop better the role of the chemistry in the behaviour. Swelling
was therefore analysed by imposing on the sample a chemical loading while maintaining constant
the axial stress. Monovalent and divalent salts which were used with various concentrations are
the sodium chloride (NaCl), the potassium chloride (KCl) and the calcium chloride (CaCl2). The
foreseen objective was to analyze the effect of the chemical path with decreasing or cyclic concentrations
and to highlight the role of the solution normality, the type of salt and the anisotropy on
the axial swelling.
The experimental results obtained allowed the development of a new rheological model which takes
into account the time, the anisotropy, the applied loading and the chemistry of the solution. This
model was implemented in a finite element code to simulate simple cases and to prove its validity.
Document type :
Theses
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https://pastel.archives-ouvertes.fr/tel-00011993
Contributor : Jad Wakim <>
Submitted on : Monday, March 20, 2006 - 8:10:09 PM
Last modification on : Wednesday, October 14, 2020 - 4:02:29 AM
Long-term archiving on: : Tuesday, June 15, 2010 - 4:31:53 PM

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  • HAL Id : tel-00011993, version 1

Citation

Jad Wakim. Influence des solutions aqueuses sur le comportement mécanique des roches argileuses. Sciences de l'ingénieur [physics]. École Nationale Supérieure des Mines de Paris, 2005. Français. ⟨tel-00011993⟩

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