G. Backblom et Cd. Martin, Recent experiments in hard rocks to study the excavation response: Implications for the performance of a nuclear waste geological repository, TUNN UNDERG, 14(3), 1999, pp. 377-394
Major excavation response experiments in granitic rocks have recently been
finalized in Canada, Japan and Sweden. There is good understanding of the p
hysical processes involved in developing a failed and damaged zone around a
n underground opening in crystalline hard racks. Useful and feasible invest
igation methodology exists for the description of the mechanical response.
The effect of drill-and-blast and mechanical excavation on the extent of th
e damaged zone is also clarified. However, accurate description of the hydr
ogeological response to the excavation may warrant further studies. The res
ults derived from the experiments are useful to assess the overall impact o
n the post-closure performance of a geological repository for high-level, l
ong-lived nuclear waste. Whether or not an excavation failed/damaged/distur
bed zone exists is not crucial to the overall safety of a geological reposi
tory, but excluding the zone may result in nonconservative estimation of ma
ximum radiation dose. The experiments in Canada, Japan and Sweden have not
yet dealt explicitly with consequences of the repository being operated for
several decades before closure, nor with the thermomechanical effects. Suc
h effects may also be of importance for the long-term post-closure function
of the repository. (C) 1999 Published by Elsevier Science Ltd. All rights
reserved.