Experimental Study of Sealing Capacity of Clay Rock

In argillaceous rocks, self-sealing of fractures generated by the excavation of underground repositories can be expected due to combined impact of rock compression, backfill resistance, and clay swelling during the post-closure phase. The sealing process is determined by the deformability and swelling capacity of the host rock and the backfill as well as by the boundary conditions. As a crucial factor for the long-term safety of repositories, the sealing behaviour of fractures in claystone has been experimentally investigated by GRS on the Callovo-Oxfordian argillite (COX) at Bure in France and the Opalinus clay (OPA) at Mont-Terri in Switzerland under relevant repository conditions.