Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
770625 | Engineering Fracture Mechanics | 2012 | 12 Pages |
Argillites are considered worldwide as potential host rock for high level radioactive waste given the low permeability and strong adsorption potential. However, the excavation of the galleries of a repository would produce a disturbed zone around the boundaries rich of new fractures which may enhance the conductivity of the rock along the gallery axis.Several mine-by experiments have been performed in underground rock labs to investigate the features of the disturbed zone. In Mont Terri URL (Kanton Jura, Switzerland) the EZ-B experiment was specifically conceived for the measurement of excavation induced fractures around a small chamber. The host rock of the URL is a particularly compact and resistant argillite, known as the Opalinus Clay (OPA) excavated and OPA samples were subjected to fracture mechanics tests at the rock mechanics lab of IGAG-CNR in Torino, Italy. The tests aimed at the understanding aspects of the fracturing process occurring in OPA of Mont Terri, which may be considered a transversely isotropic geomaterial, whose planes of isotropy coincide with the bedding.
► Opalinus Clay is a transversely isotropic material. ► SCB tests are effective in deriving the FM orientation-dependent parameters. ► The experimental tests are efficiently simulated by the Cohesive Crack Model. ► Opalinus Clay is affected by a relevant size effect.