25 years of underground engineering in a plastic clay formation: the HADES underground research facility

The Boom Clay layer, a tertiary plastic clay, was chosen as a study case for the geological disposal of high level and long-lived radioactive waste. For R&D purposes, the underground research facility HADES was constructed at a depth of 223m. The construction started in 1980 with the sinking of a shaft, and the facility was expanded several times since then. Construction techniques and the level of understanding of hydro-mechanical processes have very much evolved throughout the years. This paper describes the construction techniques used at HADES and focuses on the most recent extension. A 80m long gallery was constructed using industrial techniques and the excavation was accompanied by an extensive instrumentation and characterisation programme.