Advertisement

Rock Mechanics and Rock Engineering

, Volume 47, Issue 1, pp 57–70 | Cite as

Laboratory and In Situ Simulation Tests of the Excavation Damaged Zone Around Galleries in Opalinus Clay

  • Vincent Labiouse
  • Tim Vietor
Original Paper

Abstract

In the context of nuclear waste disposal in clay formations, laboratory and in situ simulation experiments were performed to study at reduced scale the excavation damaged zone (EDZ) around tunnels in the indurated Opalinus Clay at Mont Terri, Switzerland. In the laboratory, thick-walled hollow cylindrical specimens were subjected to a mechanical unloading mimicking a gallery excavation. In samples cored parallel to bedding, cracks sub-parallel to the bedding planes open and lead to a buckling failure in two regions that extend from the borehole in the direction normal to bedding. The behaviour is clearly anisotropic. On the other hand, in experiments performed on specimens cored perpendicular to bedding, there is no indication of failure around the hole and the response of the hollow cylinder sample is mainly isotropic. The in situ experiment at Mont Terri which consisted in the overcoring of a resin-injected borehole that follows the bedding strike of the Opalinus Clay showed a striking similarity between the induced damaged zone and the fracture pattern observed in the hollow cylinder tests on samples cored parallel to bedding and such a bedding controlled “Excavation” Damaged Zone is as well consistent with the distinct fracture patterns observed at Mont Terri depending on the orientation of holes/galleries with respect to the bedding planes. Interestingly, the damaged zone observed in the hollow cylinder tests on samples cored parallel to bedding and in situ around URL galleries is found to develop in reverse directions in Boom Clay (Mol) and in Opalinus Clay (Mont Terri). This most probably results from different failure mechanisms, i.e. shear failure along conjugated planes in the plastic Boom Clay, but bedding plane splitting and buckling in the indurated Opalinus Clay.

Keywords

Hollow cylinder test In situ simulation test Excavation damaged zone X-ray computed tomography Opalinus Clay Nuclear waste disposal 

Notes

Acknowledgments

The TIMODAZ project is co-funded by the European Commission and performed as part of the sixth EURATOM Framework Programme for nuclear research and training activities (2002-2006) under contract FI6 W-CT-2007-036449. The Mont Terri URL is an international project of 14 partners from 7 countries and is lead by Director P. Bossart of the Federal Office for Topography, Swisstopo. The support of the Mont Terri staff under the supervision of the Project Manager C. Nussbaum is gratefully acknowledged. Further acknowledgements go to Laurent Gastaldo and Shuang You who contributed to the LMR-EPFL experiment and to Martine Bernasconi of the Department of Diagnostic and Interventional Radiology of the CHUV (Lausanne Cantonal Hospital) for the X-ray computed tomography scans of the hollow cylinders. Finally, the Authors are grateful to two anonymous reviewers, whose suggestions and comments helped to improve the quality of the paper.

References

  1. Bardertscher N, Girardin C, Nussbaum C (2008) SE-H Experiment: EDZ structural analysis of resin impregnated sections from BSE-3 overcore. Mont Terri Technical Note TN 2008-15, Saint Ursanne, SwitzerlandGoogle Scholar
  2. Bernier F, Li XL, Bastiaens W, Ortiz L, Van Geet M, Wouters L, Frieg B, Blümling P, Desrues J, Viaggiani G, Coll C, Chanchole S, De Greef V, Hamza R, Malinsky L, Vervoort A, Vanbrabant Y, Debecker B, Verstraelen J, Govaerts A, Wevers M, Labiouse V, Escoffier S, Mathier J-F, Gastaldo L, Bühler C (2006) SELFRAC: Fractures and self-healing within the excavation disturbed zone in clays: Final technical report EUR 22585. Commission of the European Communities, LuxembourgGoogle Scholar
  3. Blümling P, Bernier F, Lebon P, Martin CD (2007) The excavation-damaged zone in clay formations—time-dependent behaviour and influence on performance assessment. Phys Chem Earth 32(5–14):588–599CrossRefGoogle Scholar
  4. Bossart P, Meier PM, Moeri A, Trick T, Mayor J-C (2002) Geological and hydraulic characterisation of the excavation disturbed zone in the Opalinus Clay of the Mont Terri Rock Laboratory. Eng Geol 66:19–38CrossRefGoogle Scholar
  5. Brehm A, Ward C, Bradford D, Riddle G (2006) Optimizing a deepwater subsalt drilling program by evaluating anisotropic rock strength effects on wellbore stability and near-wellbore stress effects on the fracture gradient. In: Proceedings of IADC/SPE Drilling Conference, Miami, Florida, USA, IADC/SPE 98227Google Scholar
  6. Cook JM, Goldsmith G, Bailey L, Audibert A, Bieber M-T (1994) X-ray tomographic study of the influence of bedding plane orientation on shale swelling. In: Proceedings of SPE/ISRM Eurock 1994, Delft, The Netherlands, pp 267–274Google Scholar
  7. Labiouse V, Sauthier C, You S (2013) Hollow cylinder simulation experiments of galleries in Boom Clay formation. Rock Mech Rock Eng. doi: 10.1007/s00603-012-0332-0 (this issue)
  8. Martin CD, Lanyon GW (2003) Measurement of in situ stress in weak rocks at Mont Terri Rock Laboratory, Switzerland. Int J Rock Mech Min Sci 40:1077–1088CrossRefGoogle Scholar
  9. Nagra (2002) Projekt Opalinuston: Synthese der geowissenschaftlichen Untersuchungsergebnisse. Technischer Bericht 02-03. Nagra, Wettingen, SwitzerlandGoogle Scholar
  10. Nagra (2008): Vorschlag geologischer Standortgebiete für das SMA- und das HAA-Lager, Geologische Grundlagen. Technischer Bericht 08-04, Nagra, Wettingen, SwitzerlandGoogle Scholar
  11. Økland D, Cook JM (1998) Bedding-related borehole instability in high-angle wells. In: Proceedings of SPE/ISRM Eurock 1998, Trondheim, Norway, pp 413–421Google Scholar
  12. Popp T, Salzer K, Minkley W (2008) Influence of bedding planes to EDZ-evolution and the coupled HM properties of Opalinus Clay. Phys Chem Earth 33:374–387CrossRefGoogle Scholar
  13. Seeska R, Lux KH, Hesser JBB experiment: long term deformation behaviour of boreholes. Mont Terri Technical Note TN 2011-04, Saint Ursanne, Switzerland (in preparation)Google Scholar
  14. Tsang C-F, Bernier F (2004) Definitions of excavation disturbed zone and excavation damaged zone. European Commission Report EUR 21028 EN, LuxembourgGoogle Scholar
  15. Van Marcke P, Bastiaens W (2010) Excavation induced fractures in a plastic clay formation: observations at the HADES URF. J Struct Geol 32:1677–1684CrossRefGoogle Scholar
  16. Vietor T, Blümling P, Armand G (2006) Failure mechanisms of the Opalinus Clay around underground excavations. In: Proceedings of Eurock 2006, ISRM reg symp, Liège, Belgium, pp 479–484Google Scholar
  17. Vietor T, Alheid HJ, Blümling P, Bossart P, Gibert D, Heusermann F, Nicollin S, Nussbaum C, Plischke I, Schuster K, Shin K, Spies T (2008) Rock mechanics experiments. In: Bossart, Thury (eds) Mont Terri Rock Laboratory Project, Programme 1996 to 2007 and Results. Reports of the Swiss Geological Survey 3, WabernGoogle Scholar
  18. Wileveau Y, Bernier F (2008) Similarities in the hydromechanical response of Callovo-Oxfordian clay and Boom Clay during gallery excavation. Phys Chem Earth 33:343–349CrossRefGoogle Scholar

Copyright information

© Springer-Verlag Wien 2013

Authors and Affiliations

  1. 1.Rock Mechanics Laboratory (LMR), Ecole Polytechnique Fédérale de Lausanne (EPFL)LausanneSwitzerland
  2. 2.National Cooperative for the Disposal of Radioactive Waste (NAGRA)WettingenSwitzerland

Personalised recommendations