Statistical analyses of pressure signals, hydrogeologic characterization and evolution of Excavation Damaged Zone (claystone sites of Mont Terri and Tournemire)

Abstract

We present statistical analyses of pore pressure and other signals, aimed at characterizing the properties of a geologic porous medium and, particularly, of the Excavation Damaged Zone ("EDZ") around underground galleries. The purpose is not only to identify the material properties, but also to quantify their evolution during excavation (creation of an EDZ). The methods are applied to two Underground Research Laboratories ("URL’s") in claystone sites: Mont Terri in Switzerland (gallery Ga98) and Tournemire in France (gallery Ga03). This work is part of the LP 14 experiment, an international research program of the Mont Terri Consortium, aimed at assessing the isolation properties of claystone as a potential geologic repository for radioactive waste (LP 14 experiment: Long term Pressure experiment, phase 14).