ABSTRACT

Abstract: The Mont Terri Project is an international research project to investigate the hydrogeological, geochemical and geotechnical characterization of the Opalinus Clay formation. Clay formations are being considered in various countries for deep geological disposal of radioactivewaste. Our research is carried out in the genericMont Terri rock laboratory, an underground facility near the security gallery of the Mont Terri highway tunnel in northwestern Switzerland. Sixteen partners from eight countries participate in this project. The experiments are designed to better understand the processes and mechanisms in undisturbed argillaceous formations. These include experiments related to excavation-and repository-induced perturbations and to repository performance during operational and post-closure phases. Here we outline a timescale for key processes affecting repository performance and relate the ongoing experiments to this timescale. The main focus is placed on the applied in-situ testing methods and the corresponding equipment and materials. We start with excavation and drilling techniques, then proceed to hydrogeological, geochemical and geophysical experiments. Finally, a recent mine-by experiment is presented where acoustic emission signals were used to identify the temporal and spatial evolution of the excavation damaged zone.