Abstract
Ultra-long-term storage of spent nuclear fuel and other waste products is most likely to be accomplished through the construction and safe closure of deep geological repositories (DGRs). Around the world, numerous countries are planning, designing and in some cases, building such repositories in sound rock between 400 and 1000 m below surface. In Ontario, Canada, both crystalline (granite, gneiss, etc.) and sedimentary (limestone) are being considered as host formations. A critical element of the host rock (the geo-barrier) is the susceptibility to excavation-induced damage and the long-term evolution of this fracture damage over the lifetime of the repository. The excavation damage zone, EDZ, can form a pathway for the migration of radionuclides from the repository, bypassing seals and internal barrier structures. The Cobourg Limestone is a candidate formation for DGR construction in Ontario, Canada. The long-term performance of this barrier rock may be controlled in part by internal structures including pseudo-bedding in the form of varying clay mineral content and an argillaceous/calcite nodular structure. Typically, geotechnical assessment, analysis and design are based on standard rock properties obtained from laboratory testing on 50–75 mm diameter samples and the occurrence (if any) of jointing. Neglected are the impacts of the internal texture within the limestone. The potential impacts of these structures on EDZ evolution are numerically explored in this paper to provide a schematic illustration of their potential importance for ultra-long-term behaviour. It is evident from this scoping study that the physical (and geological) nature of the bedding structures as well as the internal intra-bed fabric plays as significant a role in behaviour as does the nominal as-measured bulk properties.
Similar content being viewed by others
References
Boisson J (2005) Clay club catalogue of characteristics of argillaceous rocks. OECD/NEA/RWMC/IGSC. Working Group on measurement & Physical understanding of Groundwater flow through argillaceous media. Report NEA n° 4436
Day JJ, Diederichs MS, Hutchinson DJ (2017) New direct shear testing protocols and analyses for fractures and healed intra-block rockmass discontinuities. Eng Geol 229:53–72
Dershowitz WS, Einstein HH (1988) Characterizing rock joint geometry with joint system models. Rock Mech Rock Eng 21:21–51
Diederichs MS (2007) CGS Geocolloquium Award Lecture: damage and spalling prediction criteria for deep tunnelling. Can Geotech J 44(9):1082–1116
Eberhardt E, Diederichs M (2017) Review of the evolution of the mechanical stability and hydraulic conductivity around the rock vaults of SFR. Swedish Radiation Safety Authority—SSM 2017: 31. (Available at www.stralsakerhetsmyndigheten.se). 317
Ghazvinian E, Diederichs MS, Labrie D, Martin D (2015) An investigation on the fabric type dependency of crack damage thresholds in brittle rocks. Geotech Geol Eng 33(6):1409–1429
Goodman RE, Taylor RL, Brekke RL (1968) A model for the mechanics of jointed rock. J Soil Mech Found Div 94(3):637–659
Jaczkowski E, Ghazvinian E, Diederichs M (2017) Uniaxial compression and indirect tensile testing of cobourg limestone: influence of scale, saturation and loading rate. Technical Report: NWMO-TR-2017-17
Lan H, Martin CD, Hu B (2010) Effect of heterogeneity of brittle rock on micromechanical extensile behaviour during compression loading. J Geophys Res 115:B01202
NWMO (2011) Geosynthesis. Nuclear Waste Management Organization Report NWMO DGR-TR-2011–11, Toronto
Paraskevopoulou C, Perras M, Diederichs M, Löw S, Lam T, Jensen M (2018) Time-dependent behaviour of brittle rocks based on static load laboratory testing. J Geotech Geol Eng 36(1):337–376
Pitts M (2017) Thermal properties of the Cobourg Limestone. MASc Thesis. Queen’s University
Sinha S, Walton G (2018) Application of micromechanical modeling to prediction of in-situ rock behavior. Proceedings of the 52nd US Rock Mechanics/Geomechanics Symposium held in Seattle, Washington, USA, 17–20 June 2018. ARMA 18–265.
Acknowledgements
The Natural Sciences and Engineering Research Council of Canada through CRD grants held by Dr. Mark S. Diederichs, P.Eng., FEIC and the Nuclear Waste Management Organization of Canada have financially supported this research.
Author information
Authors and Affiliations
Corresponding author
Additional information
Publisher's Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Rights and permissions
About this article
Cite this article
Diederichs, M.S., Day, J.J. An Illustrative Study of the Potential Sensitivity, of Predicted Long-Term EDZ Development, to Internal Fabric of Argillaceous Limestone. Rock Mech Rock Eng 55, 2805–2819 (2022). https://doi.org/10.1007/s00603-021-02602-z
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00603-021-02602-z