Study of the Pasquasia underground cavity

The reliability of the geological disposal of radioactive wastes have to be verified both by laboratory and on site research, under both surface and underground conditions. The tests carried out under high lithostatic stress can allow extrapolations to be made having absolute value at the depths planned for the construction of the repository. On the area around the Pasquasia mine, a detailed geological mapping (1: 5000 scale) has been carried out. For the purpose of studying the effects induced by the advancement of the excavation's face into the clayey mass and over the cross section of the transversal tunnel, several measurement stations were installed (multibase straingauges, convergency rods, pressure cells, centering and concrete straingauges). Structural observations were made on both the fronts and the walls of the tunnel for the purpose of characterizing the mechanical behaviour of a clayey mass. The 37 cubic blocks, their sides measuring measurement 30cm, along 72 samples collected during the excavation, have been analyzed from different point of view (sedimentological, mineralogical, geochemical, micropaleontological, interstitial water content, thermal properties, etc). After the excavation of the tunnel and the installation of the geotechnical stations, the measurements have been carried on up to March 1987. At this date the work programme has been unfortunately stopped by local authorities unfoundly suspecting Pasquasia mine would be used as waste repository