Euradwaste '08 - EU Bookshop - Europa

cussed. In addition, a simple coupling between mechanical (i.e. damage) and hydraulical properties
seems to be unlikely. Although it was demonstrated that the dilatancy concept is also valid in clay
rocks, it‘s application is much more difficult due to the overlapping effects of the porous rock matrix
and anisotropy due to bedding.
The 2D-simulation of the EDZ around a tunnel under the site specific conditions of the Mont Terri
Site demonstrated the capability of the new approach. As came out by the modelling results, the geometry
of the EDZ during excavation is mainly controlled by the instantaneous reaction of the rock
mass on the anisotropic stress regime (elasto-plastic behaviour stress induced tensile failures at
the wall) and by the overlapping bedding plane weakness ( tensile and shear fractures) which
fairly well agrees to in situ observations [3].
So far, we can conclude that high sophisticated rock-mechanical constitutive models are available
to model the development of the EDZ from a mechanical point of view [1, 3]. But looking on the
real in-situ-conditions it becomes obvious that more understanding of the complex effects of humidity
and pore pressures is required for their numerical implementation into the existing constitutive
models. Nevertheless possible consideration of time-dependent effects, i.e. creep, can be easily
done by determining the necessary parameters for the viscous part of the MINKLEY-constitutive
model. As recommendation for future work we have to conclude that more experimental lab and
field investigation are necessary to describe the complex THMC-behaviour of argillaceous clays,
mainly separating effects due to drained and un-drained conditions.
5. Acknowledgements
The studies presented have been funded as part of the NF-PRO jointly by the European Commission
under the 6 th Euratom Research and Training Framework Programme on Nuclear Energy,
(2002-2006), contract FI6W-CT2003-02389, and the German Federal Ministry of Research and
Education under contract 02 E 9874.
References
[1] Popp, T. & Salzer, K., 2007. Impact of bedding planes to coupled HM properties of the damaged
rock – combined rock mechanical laboratory investigations and modelling. NF-PRO Deliverable
4.2.15: Final report (2007-10-01).
[2] Popp, T. & Salzer, K., 2007. Anisotropy of seismic and mechanical properties of Opalinus
clay during triaxial deformation in a multi-anvil apparatus. Physics and Chemistry of the
Earth, Parts A/B/C, 32, 8-14, 879-888.
[3] Blümling, P. & Konietzky, H., 2003. Development of an excavation disturbed zone in claystone
(Opalinus Clay). Geotechnical measurements and modelling: Proceedings of the international
symposium, 23-25 September 2003, Karlsruhe, Germany; Natau O., Fecker, E., Pimentel
E. (eds.); Lisse [et al.]: A.A.Balkema Publishers, 127-132.
481