Mechanical interpretations of the homogeneous nature of bentonite due to swelling
Published:January 01, 2014
I. Kobayashi, K. Suzuki, H. Asano, P. Sellin, C. Svemar, M. Holmqvist, 2014. "Mechanical interpretations of the homogeneous nature of bentonite due to swelling", Clays in Natural and Engineered Barriers for Radioactive Waste Confinement, S. Norris, J. Bruno, M. Cathelineau, P. Delage, C. Fairhurst, E. C. Gaucher, E. H. Höhn, A. Kalinichev, P. Lalieux, P. Sellin
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To achieve the high sealing capability required for the bentonite engineered barriers used in geological disposal facilities for radioactive waste, the bentonite should be highly compacted. Previous investigation of methods to enable such compaction has revealed that the construction methods used have an impact on the density distribution. However, these investigations focused on achieving the required average dry density in the bentonite barriers and little attention has been paid to the distribution of dry density. As a result, there has been a lack of understanding of how the construction method used affects this distribution, which is highly pertinent to the evaluation of the long-term performance of bentonite engineered barriers.
This paper first describes the residual density distribution after resaturation and then highlights how swelling behaviour can be studied and evaluated based on elasto-plastic theory. The conceptual understanding is that the buffer does not swell to achieve an entirely homogeneous density, but will reach an equilibrium state with a remaining gradient.
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Clays in Natural and Engineered Barriers for Radioactive Waste Confinement
This Special Publication contains 43 scientific studies presented at the 5th conference on ‘Clays in natural and engineered barriers for radioactive waste confinement’ held in Montpellier, France in 2012. The conference and this resulting volume cover all the aspects of clay characterization and behaviour considered at various temporal and spatial scales relevant to the confinement of radionuclides in clay, from basic phenomenological process descriptions to the global understanding of performance and safety at repository and geological scales. Special emphasis has been given to the modelling of processes occurring at the mineralogical level within the clay barriers.
The papers in this Special Publication consider research into argillaceous media under the following topic areas: large-scale geological characterization; clay-based concept/large-scale experiments; hydrodynamical modelling; geochemistry; geomechanics; mass transfer/gas transfer; mass transfer mechanisms.
The collection of different topics presented in this Special Publication demonstrates the diversity of geological repository research.