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Experimental Study of the Brittle Behavior of Clay shale in Rapid Unconfined Compression

Amann, Florian ; Button, Edward ; Evans, Keith ; Gischig, Valentin ; Blümel, Manfred

In: Rock Mechanics and Rock Engineering, 2011, vol. 44, no. 4, p. 415-430

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    Titel
    • Experimental Study of the Brittle Behavior of Clay shale in Rapid Unconfined Compression
    Autor
    • Amann, Florian. Engineering Geology, Institute of Geology, Swiss Federal Institute of Technology, Sonneggstrasse 5, 8092, Zurich, Switzerland
    • Button, Edward. Geoconsult, Pvt. Ltd, Plot 473, Industrial Estate, Udyog Vihar, Sector 19, Phase V, Gurgaon, India
    • Evans, Keith. Engineering Geology, Institute of Geology, Swiss Federal Institute of Technology, Sonneggstrasse 5, 8092, Zurich, Switzerland
    • Gischig, Valentin. Engineering Geology, Institute of Geology, Swiss Federal Institute of Technology, Sonneggstrasse 5, 8092, Zurich, Switzerland
    • Blümel, Manfred. Institute for Rock Mechanics and Tunnelling, Graz University of Technology, Rechbauerstrasse 12, 8010, Graz, Austria
    Dokumententyp
    • Postprint
    Sprache
    • Englisch
    Veröffentlicht in
    • Rock Mechanics and Rock Engineering, 2011, vol. 44, no. 4, p. 415-430. Springer Vienna
    Andere elektronische Ausgabe
    OAI-PMH-ID
    • oai:doc.rero.ch:314047
    Summary
    The mechanical behavior of clay shales is of great interest in many branches of geo-engineering, including nuclear waste disposal, underground excavations, and deep well drilling. Observations from test galleries (Mont Terri, Switzerland and Bure, France) in these materials have shown that the rock mass response near the excavation is associated with brittle failure processes combined with bedding parallel shearing. To investigate the brittle failure characteristics of the Opalinus Clay recovered from the Mont Terri Underground Research Laboratory, a series of 19 unconfined uniaxial compression tests were performed utilizing servo-controlled testing procedures. All specimens were tested at their natural water content with loading approximately normal to the bedding. Acoustic emission (AE) measurements were utilized to help quantify stress levels associated with crack initiation and propagation. The unconfined compression strength of the tested specimens averaged 6.9MPa. The crack initiation threshold occurred at approximately 30% of the rupture stress based on analyzing both the acoustic emission measurements and the stress-strain behavior. The crack damage threshold showed large variability and occurred at approximately 70% of the rupture stress