Seismic and mechanical properties of Opalinus Clay: comparison between sandy and shaly facies from Mont Terri (Switzerland)
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- Authors:
- SIEGESMUND, S
POPP, T
KAUFHOLD, A
DOHRMANN, R
GRÄSLE, W
HINKES, R
SCHULTE-KORTNACK, D - Author Affiliations:
- Geowissenschaftliches Zentrum der Universität Göttingen, Goldschmidtstr. 3, 37077 Göttingen, Germany
Institut für Gebirgsmechanik GmbH Leipzig, Friederikenstr, 60, 04279 Leipzig, Germany
BGR/LBEG, Stilleweg 2, 30655 Hannover, Germany
Intstitut für Geowissenschaften, Christian-Albrechts-Universität zu Kiel, Ludewig-Meyn-Strasse 12, 24118 Kiel, Germany - Source:
- Environmental earth sciences (Print). 71(8):3737-3749
- Publication Date:
- 2014-01-01
- Language:
- English
- Abstract:
- For the safe disposal of high-level radioactive waste, different host rocks are currently being considered. The favorable properties of clay are low permeability, some retention capacity concerning radionuclides, and the ability to self-seal cracks and fissures, e.g. by swelling or time-dependent compaction creep. In Switzerland, the Jurassic Opalinus Clay is envisaged as a potential host rock which—at Mont Terri—is subdivided into the sandy, shaly, and carbonate-rich facies, the latter being less abundant. For long-term safety assessments, the understanding of the relations of properties (e.g. mineralogical composition and microstructure) and performance (e.g. mechanical behavior) of clays and clay stones is essential. In the case of the sandy Opalinus Clay, the mechanical strength increases with increasing carbonate content, because carbonates form the matrix. The mineralogical investigation of a set of sandy facies samples proved a significantly larger carbonate content (20-40 mass %) when compared to the shaly facies (10-20 mass %). The carbonates of the shaly Opalinus Clay, on the other hand, are mostly localized fossils aligned parallel to the bedding, acting as predetermined breaking points. Image analysis of SEM images of polished sections proved the determined microstructural differences. In addition, carbonate particles of the sandy facies are mostly isometric, whereas carbonate particles of the shaly facies cover a greater range of shapes. The mechanical tests were accompanied by investigations of the p- and s-wave velocities, which revealed that the anisotropy of the sandy facies is less pronounced than sedimentological analyses would suggest. The mechanical strength, which, for the first time, presents results of real triaxial tests of the sandy facies. The samples of the sandy facies exhibit a failure strength of σeff,B, approximately twice as high as was found for the shaly facies considering the deformation axis parallel to the bedding. Similar values were obtained when measuring perpendicularly to the bedding.
- Notes:
- Earth sciences
- Subjects:
- Environment
Environnement
Geology
Géologie
Pollution
Sciences exactes et technologie
Exact sciences and technology
Terre, ocean, espace
Earth, ocean, space
Sciences de la terre
Earth sciences
Géologie de l'ingénieur et de l'environnement. Géothermie
Engineering and environment geology. Geothermics
Pollution, géologie de l'environnement
Pollution, environment geology
Formations superficielles
Surficial geology
Quaternaire marin et continental
Marine and continental quaternary
Mésozoïque
Mesozoic
Phanérozoïque
Phanerozoic
Fanerozoico
Roche clastique
clastic rocks
Roca clástica
Roche sédimentaire
sedimentary rocks
Roca sedimentaria
Analyse image
image analysis
Análisis imagen
Argile
clay
Arcilla
Carbonate
carbonates
Carbonato
Compaction
compaction
Compactación
Déchet haute activité
high-level waste
Déchet radioactif
radioactive waste
Residuos radioactivos
Fissure
fissures
Fisura
Fluage
creep
Fluencia
Gonflement
swelling
Inflamiento
Jurassique
Jurassic
Jurásico
Litage
bedding
Estratificación fina
Microstructure
microstructures
Microestructura
Onde S
S-waves
Onda S
Particule
particles
Perméabilité
permeability
Permeabilidad
Pollution
pollution
Polución
Propriété mécanique
mechanical properties
Propiedad mecánica
Radionucléide
radionucleids
Radionucleido
Roche hôte
host rocks
Roca huesped
Résistance mécanique
strength
Resistencia mecánica
Rétention
retention
Section polie
polished sections
Superficie pulida
Sécurité
safety
Vitesse
velocity
Velocidad
Dilatancy
Mechanical strength
Microfabric
Mineralogy
Opalinus Clay
Radioactive waste
Seismic anisotropy
Shaly and sandy facies
Triaxial pressure apparatus - Geography:
- Europe Centrale
Central Europe
Europa central
Europe
Europa
Suisse
Switzerland
Suiza - Format:
- Academic Journal
- Database:
- PASCAL Archive
- Journal:
- Environmental earth sciences (Print)
- Volume:
- 71
- Issue:
- 8
- Page Start:
- 3737
- Page Count:
- 13
- ISSN:
- 18666280
- Publisher:
- Heidelberg: Springer, 2014.
- Document Type:
- Article
- Physical Description:
- print, 3/4 p
