Dielectric relaxation behavior of Callovo-Oxfordian clay rock: A hydraulic-mechanical-electromagnetic coupling approach

  • Water content is a key parameter to monitor in nuclear waste repositories such as the planed underground repository in Bure, France, in the Callovo-Oxfordian (COx) clay formation. High-frequency electromagnetic (HF-EM) measurement techniques, i.e., time or frequency domain reflectometry, offer useful tools for quantitative estimation of water content in porous media. However, despite theWater content is a key parameter to monitor in nuclear waste repositories such as the planed underground repository in Bure, France, in the Callovo-Oxfordian (COx) clay formation. High-frequency electromagnetic (HF-EM) measurement techniques, i.e., time or frequency domain reflectometry, offer useful tools for quantitative estimation of water content in porous media. However, despite the efficiency of HF-EM methods, the relationship between water content and dielectric material properties needs to be characterized. Moreover, the high amount of swelling clay in the COx clay leads to dielectric relaxation effects which induce strong dispersion coupled with high absorption of EM waves. Against this background, the dielectric relaxation behavior of the clay rock was studied at frequencies from 1 MHz to 10 GHz with network analyzer technique in combination with coaxial transmission line cells. For this purpose, undisturbed and disturbed clay rock samples were conditioned to achieve a water saturation range from 0.16 to nearly saturation. The relaxation behavior was quantified based on a generalized fractional relaxation model under consideration of an apparent direct current conductivity assuming three relaxation processes: a high-frequency water process and two interface processes which are related to interactions between the aqueous pore solution and mineral particles (adsorbed/hydrated water relaxation, counter ion relaxation and Maxwell-Wagner effects). The frequency-dependent HF-EM properties were further modeled based on a novel hydraulic-mechanical-electromagnetic coupling approach developed for soils. The results show the potential of HF-EM techniques for quantitative monitoring of the hydraulic state in underground repositories in clay formations.show moreshow less

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Metadaten
Document Type:Article
Author: Norman WagnerORCiDGND, Thierry Bore, Jean-Charles Robinet, Daniel Coelho, Frederic Taillade, Sylvie Delepine-Lesoille
DOI (Cite-Link):https://doi.org/10.1002/jgrb.50343Cite-Link
URN (Cite-Link):https://nbn-resolving.org/urn:nbn:de:gbv:wim2-20170428-31681Cite-Link
Parent Title (English):Journal of Geophysical Research: Solid Earth
Language:English
Date of Publication (online):2017/04/28
Year of first Publication:2013
Release Date:2017/04/28
Publishing Institution:Bauhaus-Universität Weimar
Institutes and partner institutions:An-Institute / Materialforschungs- und -prüfanstalt an der Bauhaus-Universität
First Page:4729
Last Page:4744
GND Keyword:Lehm; Relaxation; Wassergehalt; Reflektometrie
Dewey Decimal Classification:600 Technik, Medizin, angewandte Wissenschaften / 620 Ingenieurwissenschaften
BKL-Classification:51 Werkstoffkunde / 51.40 Werkstoffe für bestimmte Anwendungsgebiete
58 Chemische Technik, Umwelttechnik, verschiedene Techno- / 58.54 Radioaktive Abfälle und ihre Behandlung
Licence (German):License Logo Zweitveröffentlichung