A new gallery (excavated diameter 4.89m) was recently constructed at the underground research facility HADES (Mol, Belgium) located at a depth of 223m in a plastic clay layer. An industrial excavation technique was used. The EDZ around the gallery is studied by observing macro-fractures and pore pressure distribution. The fractured zone extends at least lm into the host rock; this value will be verified during the EC SELFRAC project. The radius of the Hydraulic Disturbed Zone (HDZ) is at least 20m and the HDZ is anisotropic. Gallery construction will always induce an EDZ but it is shown that industrial excavation techniques can limit its extent. From a depth of 1.3m into the host rock, installed piezometers are sealed off from the gallery by the converging clay. From a distance of 5. lm into the host rock, the influence of the excavation on permeability is limited.
|Office for official publications of the European Communities
|2003 - European Commission cluster conference and workshop on the impact of the excavation disturbed or damaged zone on the performance of radioactive waste geological repositories
|2003-11-03 → 2003-11-05