Articles | Volume 13, issue 5
https://doi.org/10.5194/se-13-901-2022
© Author(s) 2022. This work is distributed under
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the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/se-13-901-2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
16 May 2022
Research article |
| 16 May 2022
| 16 May 2022
Failure mode transition in Opalinus Clay: a hydro-mechanical and microstructural perspective
Lisa Winhausen
CORRESPONDING AUTHOR
Department of Engineering Geology and Hydrogeology, RWTH Aachen
University, Lochnerstraße 4–20, 52064 Aachen, Germany
Kavan Khaledi
Department of Engineering Geology and Hydrogeology, RWTH Aachen
University, Lochnerstraße 4–20, 52064 Aachen, Germany
Mohammadreza Jalali
Department of Engineering Geology and Hydrogeology, RWTH Aachen
University, Lochnerstraße 4–20, 52064 Aachen, Germany
Janos L. Urai
Institute of Tectonics and Geodynamics, RWTH Aachen University,
Lochnerstraße 4–20, 52064 Aachen, Germany
Florian Amann
Department of Engineering Geology and Hydrogeology, RWTH Aachen
University, Lochnerstraße 4–20, 52064 Aachen, Germany
Fraunhofer IEG, Fraunhofer Research Institution for Energy
Infrastructures and Geothermal Systems, Kockerellstraße 17, 52062
Aachen, Germany
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Cited articles
Amann, F., Button, E. A., Evans, K. F., Gischig, V. S., and Blümel, M.:
Experimental Study of the Brittle Behavior of Clay shale in Rapid Unconfined
Compression, Rock Mech. Rock Eng., 44, 415–430,
https://doi.org/10.1007/s00603-011-0156-3, 2011.
Amann, F., Kaiser, P., and Button, E. A.: Experimental Study of Brittle
Behavior of Clay Shale in Rapid Triaxial Compression, Rock Mech.
Rock Eng., 45, 21–33, https://doi.org/10.1007/s00603-011-0195-9,
2012.
Armand, G., Leveau, F., Nussbaum, C., de La Vaissiere, R., Noiret, A.,
Jaeggi, D., Landrein, P., and Righini, C.: Geometry and properties of the
excavation-induced fractures at the Meuse/Haute-Marne URL drifts, Rock
Mech. Rock Eng., 47, 21–41,
https://doi.org/10.1007/s00603-012-0339-6, 2014.
Attewell, P. B. and Sandford, M. R.: Intrinsic Shear Strength of a Brittle,
Anisotropic Rock – I: Experimental and Mechanical Interpretation,
Int. J. Rock Mech. Min. Sci.
Geom. Abstr., 11, 423–430, 1974.
Bésuelle, P., Viggiani, G., Desrues, J., Coll, C., and Charrier, P.: A
Laboratory Experimental Study of the Hydromechanical Behavior of Boom Clay,
Rock Mech. Rock Eng., 47, 143–155,
https://doi.org/10.1007/s00603-013-0421-8, 2014.
Bishop, A. W., Webb, D. L., and Lewin, P. I.: Undisturbed Samples of London
Clay from the Ashford Common Shaft: Strength–Effective Stress
Relationships, Géotechnique, 15, 1–31,
https://doi.org/10.1680/geot.1965.15.1.1, 1965.
Bossart, P., Meier, P. M., Moeri, A., Trick, T., and Mayor, J. C.: Geological
and hydraulic characterisation of the excavation disturbed zone in the
Opalinus Clay of the Mont Terri Rock Laboratory, Eng.
Geol., 66, 19–38, https://doi.org/10.1016/S0013-7952(01)00140-5,
2002.
Brace, W. F., Paulding, B. W., and Scholz, C.: Dilatancy in the fracture of
crystalline rocks, J. Geophys. Res., 71, 3939–3953,
https://doi.org/10.1029/JZ071i016p03939, 1966.
Braun, P., Ghabezloo, S., Delage, P., Sulem, J., and Conil, N.: Transversely
Isotropic Poroelastic Behaviour of the Callovo-Oxfordian Claystone: A Set of
Stress-Dependent Parameters, Rock Mech. Rock Eng., 54, 377–396,
https://doi.org/10.1007/s00603-020-02268-z, 2021.
Byerlee, J. D.: Brittle-ductile transition in rocks, J. Geophys. Res., 73, 4741–4750, https://doi.org/10.1029/JB073i014p04741,
1968.
Delage, P. and Tessier, D.: Macroscopic effects of nano and microscopic
phenomena in clayey soils and clay rocks, Geomech. Energ.
Environ., 27, 100177, https://doi.org/10.1016/j.gete.2019.100177, 2021.
Desai, C. S. and Siriwardane, H. J.: Constitutive laws for engineering
materials, with emphasis on geologic materials, Prentice Hall, 468 pp., ISBN 0-13-167940-6, 1984.
Desbois, G., Höhne, N., Urai, J. L., Bésuelle, P., and Viggiani, G.:
Deformation in cemented mudrock (Callovo–Oxfordian Clay) by microcracking,
granular flow and phyllosilicate plasticity: insights from triaxial
deformation, broad ion beam polishing and scanning electron microscopy,
Solid Earth, 8, 291–305, https://doi.org/10.5194/se-8-291-2017, 2017.
Djéran-Maigre, I., Tessier, D., Grunberger, D., Velde, B., and Vasseur,
G.: Evolution of microstructures and of macroscopic properties of some clays
during experimental compaction, Mar. Petrol. Geol., 15, 109–128,
https://doi.org/10.1016/S0264-8172(97)00062-7, 1998.
Evans, B., Fredrich, J. T., and Wong, T.: The brittle-ductile transition in
rocks: Recent experimental and theoretical progress, in: Geophysical
Monograph Series, Vol. 56, edited by: Duba, A. G., Durham, W. B., Handin, J.
W., and Wang, H. F., American Geophysical Union, Washington, DC, 1–20,
https://doi.org/10.1029/GM056p0001, 1990.
Favero, V., Ferrari, A., and Laloui, L.: Anisotropic Behaviour of Opalinus
Clay Through Consolidated and Drained Triaxial Testing in Saturated
Conditions, Rock Mech. Rock Eng., 51, 1305–1319, https://doi.org/10.1007/s00603-017-1398-5, 2018.
Goetze, C.: High temperature rheology of westerly granite, J. Geophys. Res.,
76, 1223–1230, https://doi.org/10.1029/JB076i005p01223, 1971.
Gramberg, J.: The axial cleavage fracture 1 Axial cleavage fracturing, a
significant process in mining and geology, Eng. Geol., 1, 31–72,
https://doi.org/10.1016/0013-7952(65)90006-2, 1965
Griggs, D. and Handin, J.: Observations on fracture and a hypothesis of
earthquakes, book chapter in Rock Deformation (A Symposium), edited by: Griggs, D.
and Handin, GSA MEMOIRS, chap. 13, 347–364, https://doi.org/10.1130/MEM79, 1960.
Haines, S. H., Kaproth, B., Marone, C., Saffer, D., and van der Pluijm, B.:
Shear zones in clay-rich fault gouge: A laboratory study of fabric
development and evolution, J. Struct. Geol., 51, 206–225,
https://doi.org/10.1016/j.jsg.2013.01.002, 2013.
Handin, J., Hager Jr., R. V., Friedman, M., and Feather, J. N.: Experimental
deformation of sedimentary rocks under confining pressure: pore pressure
tests, AAPG Bull., 47, 717–755, 1963.
Hattab, M. and Fleureau, J.-M.: Experimental analysis of kaolinite particle
orientation during triaxial path, Int. J. Numer. Anal. Meth. Geomech., 35,
947–968, https://doi.org/10.1002/nag.936, 2011.
Hattab, M., Hammad, T., Fleureau, J.-M., and Hicher, P.-Y.: Behaviour of a
sensitive marine sediment: microstructural investigation, Géotechnique,
63, 71–84, https://doi.org/10.1680/geot.10.P.104, 2013.
Heard, H. C.: Transition from brittle fracture to ductile flow in Solenhofen
limestone as a function of temperature, confining pressure, and interstitial
fluid pressure, book chapter in Rock Deformation (A Symposium), edited by: Griggs, D.
and Handin, GSA MEMOIRS, chap. 7, 193–226, https://doi.org/10.1130/MEM79-p193,1960.
Hicher, P. Y., Wahyudi, H., and Tessier, D.: Microstructural analysis of
inherent and induced anisotropy in clay, Mech. Cohes.-Frict. Mater., 5,
341–371, 2000.
Houben, M. E., Desbois, G., and Urai, J. L.: A comparative study of
representative 2D microstructures in Shaly and Sandy facies of Opalinus Clay
(Mont Terri, Switzerland) inferred form BIB-SEM and MIP methods, Mar. Petrol. Geol., 49,
143–161, https://doi.org/10.1016/j.marpetgeo.2013.10.009, 2014.
Ibanez, W. D. and Kronenberg, A. K.: Experimental deformation of shale:
Mechanical properties and microstructural indicators of mechanisms, Int. J. Rock Mech. Min. Sci. Geomech. Abstr., 30,
723–734, https://doi.org/10.1016/0148-9062(93)90014-5, 1993.
Ingram, G. M. and Urai, J. L.: Top-seal leakage through faults and
fractures: the role of mudrock properties, Geol. Soc. Lond. Spec. Publ., 158, 125–135,
https://doi.org/10.1144/GSL.SP.1999.158.01.10, 1999.
Klinkenberg, M., Kaufhold, S., Dohrmann, R., and Siegesmund, S.: Influence
of carbonate microfabrics on the failure strength of claystones, Eng. Geol., 107,
42–54, https://doi.org/10.1016/j.enggeo.2009.04.001, 2009.
Kneuker, T. and Furche, M.: Capturing the structural and compositional
variability of Opalinus Clay: constraints from multidisciplinary
investigations of Mont Terri drill cores (Switzerland), Environ. Earth Sci.,
80, 421, https://doi.org/10.1007/s12665-021-09708-1, 2021.
Kranz, R. L.: Microcracks in rocks: A review, Tectonophysics, 100, 449–480,
https://doi.org/10.1016/0040-1951(83)90198-1, 1983.
Kupferschmied, N., Wild, K.M., Amann, F., Nussbaum, C., Jaeggi, D., and
Badertscher, N.: Time-dependent fracture formation around a borehole in a
clay shale, Int. J. Rock Mech. Min. Sci., 77,
105–114, https://doi.org/10.1016/j.ijrmms.2015.03.027 ,2015.
Labiouse, V. and Vietor, T.: Laboratory and in situ simulation tests of the
excavation damaged zone around galleries in Opalinus Clay, Rock Mech. Rock Eng., 47, 57–70,
https://doi.org/10.1007/s00603-013-0389-4, 2014.
Lanyon, G. W., Martin, D., Giger, S., and Marschall, P.: Development and
evolution of the Excavation Damage Zone (EDZ) in the Opalinus Clay – A
synopsis of the state of knowledge from Mont Terri, NAGRA Arbeitsbericht NAB, Nagra (National Cooperative for the Disposal of Radioactive Waste),
14–87, 2014.
Lauper, B., Zimmerli, G. N., Jaeggi, D., Deplazes, G., Wohlwend, S.,
Rempfer, J., and Foubert, A.: Quantification of Lithological Heterogeneity
Within Opalinus Clay: Toward a Uniform Subfacies Classification Scheme Using
a Novel Automated Core Image Recognition Tool, Front. Earth Sci., 9, 645596,
https://doi.org/10.3389/feart.2021.645596, 2021.
Logan, J. M., Friedman, M., Dengo, C., Shimamoto, T., and Higgs, N.:
Experimental studies of simulated gouge and their application to studies of
natural fault zones, U.S. Geological Survey Open File Report 79-1239, 305–343, 1979.
Mäder, U.: Recipe and preparation of a simplified artificial pore water
for Opalinus Clay and “Brown Dogger” based on the Nagra reference pore
water composition, containing Na-K-Ca-Mg-Cl-SO4-HCO3, and adjusted to
atmospheric PCO2, NAGRA AN, NAGRA Report Aktennotiz, 11–159, 2011.
Menéndez, B., Zhu, W., and Wong, T.-F.: Micromechanics of brittle
faulting and cataclastic flow in Berea sandstone, J. Struct. Geol., 18, 1–16, https://doi.org/10.1016/0191-8141(95)00076-P, 1996.
Minardi, A., Giger, S. B., Ewy, R. T., Stankovic, R., Stenebråten, J.,
Soldal, M., Rosone, M., Ferrari, A., and Laloui, L.: Benchmark study of
undrained triaxial testing of Opalinus Clay shale: Results and implications
for robust testing, Geomech. Energ. Environ., 25, 100210,
https://doi.org/10.1016/j.gete.2020.100210, 2021.
Mogi, K.: Pressure Dependence of Rock Strength and Transition from Brittle
Fracture to Ductile Flow, Bull. Earth. Res. Inst., 44,
215–232, 1966.
Morgenstern, N. R. and Tchalenko, J. S.: Microscopic structures in kaolin
subjected to direct shear, Geotechnique, 17, 309–328,
https://doi.org/10.1680/geot.1967.17.4.309, 1967.
Niandou, H., Shao, J. F., Henry, J. P., and Fourmaintraux, D.: Laboratory
Investigation of the Mechanical Behaviour of Tournemire Shale, Int. J. Rock
Mech. Min. Sci., 34, 3–16, https://doi.org/10.1016/S1365-1609(97)80029-9,
1997.
Nussbaum, C., Bossart, P., Amann, F., and Aubourg, C.: Analysis of tectonic
structures and excavation induced fractures in the Opalinus Clay, Mont Terri
underground rock laboratory (Switzerland), Swiss J.
Geosci., 104, 187–210,
https://doi.org/10.1007/s00015-011-0070-4, 2011.
Nygård, R., Gutierrez, M., Bratli, R. K., and Høeg, K.:
Brittle–ductile transition, shear failure and leakage in shales and
mudrocks, Mar. Petrol. Geol., 23, 201–212,
https://doi.org/10.1016/j.marpetgeo.2005.10.001, 2006.
Oelker, A.: Deformation properties of Boom Clay: Implementation of a
multi-scale concept, No. RWTH-2019-09913. PhD Thesis, RWTH
Publifications, https://doi.org/10.18154/RWTH-2019-09913, 2020.
Ramsay, J. G., Huber, M. I., and Lisle, R. J.: The techniques of modern
structural geology: Folds and fractures, Vol. 2, Academic press, ISBN 0125769229, 1983.
Petley, D. N.: Failure envelopes of mudrocks at high confining pressures,
Geol. Soc. Lond. Spec. Publ., 158, 61–71,
https://doi.org/10.1144/GSL.SP.1999.158.01.05, 1999.
Rutter, E. H.: On the nomenclature of mode of failure transitions in
rocks, Tectonophysics, 122, 381–387,
https://doi.org/10.1016/0040-1951(86)90153-8, 1986.
Sarout, J., Esteban, L., Delle Piane, C., Maney, B., and Dewhurst, D. N.:
Elastic anisotropy of Opalinus Clay under variable saturation and triaxial
stress, Geophys. J. Int., 198, 1662–1682,
https://doi.org/10.1093/gji/ggu231, 2014.
Schuck, B., Desbois, G., and Urai, J. L.: Grain-scale deformation mechanisms
and evolution of porosity in experimentally deformed Boom Clay, J. Struct. Geol., 130, 103894, https://doi.org/10.1016/j.jsg.2019.103894,
2020.
Schuster, V., Rybacki, E., Bonnelye, A., Herrmann, J., Schleicher, A. M.,
and Dresen, G.: Experimental Deformation of Opalinus Clay at Elevated
Temperature and Pressure Conditions: Mechanical Properties and the Influence
of Rock Fabric, Rock Mech. Rock Eng., 54, 4009–4039,
https://doi.org/10.1007/s00603-021-02474-3, 2021.
Sellin, P. and Leupin, O. X.: The Use of Clay as an Engineered Barrier in
Radioactive-Waste Management – A Review, Clays Clay Mineral., 61,
477–498, https://doi.org/10.1346/CCMN.2013.0610601, 2013.
Skempton, A. W.: Some observations on tectonic shear zones, 1st ISRM
Congress, ISRM-1CONGRESS-1966-057, 1966.
Skempton, A. W.: The pore-pressure coefficients A and B, Géotechnique,
4, 143–147, https://doi.org/10.1680/geot.1954.4.4.143, 1954.
Tchalenko, J. S.: The evolution of kink-bands and the development of
compression textures in sheared clays, Tectonophysics, 6, 159–174,
https://doi.org/10.1016/0040-1951(68)90017-6, 1968.
Tchalenko, J. S.: Similarities between Shear Zones of Different Magnitudes,
Geol. Soc. Am. Bull., 81, 1625–1640,
https://doi.org/10.1130/0016-7606(1970)81[1625:SBSZOD]2.0.CO;2, 1970.
Thury, M. and Bossart, P.: The Mont Terri rock laboratory, a new
international research project in a Mesozoic shale formation, in
Switzerland, Eng. Geol., 52, 347–359,
https://doi.org/10.1016/S0013-7952(99)00015-0, 1999.
Wild, K. M. and Amann, F.: Experimental study of the hydro-mechanical
response of Opalinus Clay – Part 1: Pore pressure response and effective
geomechanical properties under consideration of confinement and anisotropy,
Eng. Geol., 237, 32–41,
https://doi.org/10.1016/j.enggeo.2018.02.012, 2018a.
Wild, K. M. and Amann, F.: Experimental study of the hydro-mechanical
response of Opalinus Clay – Part 2: Influence of the stress path on the
pore pressure response, Eng. Geol., 237, 92–101,
https://doi.org/10.1016/j.enggeo.2018.02.011, 2018b.
Winhausen, L., Klaver, J., Schmatz, J., Desbois, G., Urai, J. L., Amann, F.,
and Nussbaum, C.: Micromechanisms leading to shear failure of Opalinus Clay
in a triaxial test: a high-resolution BIB–SEM study, Solid Earth, 12,
2109–2126, https://doi.org/10.5194/se-12-2109-2021, 2021a.
Winhausen, L., Khaledi, K., Jalali, M., Urai, J. L., and Amann, F.: Data base for: Failure mode transition in Opalinus Clay: a hydro-mechanical and microstructural perspective, OSF [data set], https://osf.io/cd27s/ date (last access: 13 May 2022), 2021b.
Wong, T., David, C., and Zhu, W.: The transition from brittle faulting to
cataclastic flow in porous sandstones: Mechanical deformation, J. Geophys.
Res., 102, 3009–3025, https://doi.org/10.1029/96JB03281, 1997.
Yong, S., Loew, S., Schuster, K., Nussbaum, C., and Fidelibus, C.:
Characterisation of excavation-induced damage around a short test tunnel in
the Opalinus Clay, Rock Mech. Rock Eng., 50, 1959–1985,
https://doi.org/10.1007/s00603-017-1212-4, 2017.
Yongnian, H., Chuanyong, L., and Lanbin, S.: Microstructural Features of
Deformed Rocks across the Brittle-Ductile Transition, Phys. Chem.
Earth, 17, 11–15, https://doi.org/10.1016/0079-1946(89)90003-7, 1989.
Short summary
Triaxial compression tests at different effective stresses allow for analysing the deformation behaviour of Opalinus Clay, the potential host rock for nuclear waste in Switzerland. We conducted microstructural investigations of the deformed samples to relate the bulk hydro-mechanical behaviour to the processes on the microscale. Results show a transition from brittle- to more ductile-dominated deformation. We propose a non-linear failure envelop associated with the failure mode transition.
Triaxial compression tests at different effective stresses allow for analysing the deformation...
