The European Organization for Nuclear Research (CERN) is currently undertaking a feasibility study to build the next-generation particle accelerator named the Future Circular Collider (FCC). The planned FCC will be hosted in a 90-100 km-long tunnel in the Geneva Basin extending across western Switzerland and adjacent France. Traditionally, excavated materials from tunnelling constructions have been treated as waste. Modern thinking has shifted toward finding beneficial uses for these excavated materials. The present study provides basin-scale stratigraphic and lithotype analyses to establish a rock classification scheme within the FCC footprint. The rock classification will help to identify geological hazards and predict the beneficial application uses for the excavated materials. This characterisation is based on a thorough review and digitisation of archive subsurface data as well as an extensive set of newly acquired field and laboratory analyses. These geomechanical, petrophysical, mineralogical, geochemical and physico-chemical analyses were performed on rock material sampled at well and outcrop locations along the FCC's planned subsurface alignment, and analysed in conjunction with geophysical well-log data, resulting in a catalogue of 2'461 samples. The FCC tunnel will intersect 13 geological formations, which are classified into 25 different lithotypes across the Geneva Basin. Three geological hazards are identified to affect tunnelling construction: (1) karstic intervals in the Mesozoic Grand Essert Formation¿s Neuchâtel Member, Vallorbe and Vuache formations, predominantly associated with fractured limestone; (2) swelling rock associated with anhydrite contents up to 13 wt.\% in the Grès et Marnes Gris à gypse formation in the northern part of the basin and swelling rock associated with smectite contents of up to 17.2 wt.\% in the clay-rich Molasse Rouge formation; (3) materials that contain hydrocarbons and heavy metals that must be either treated before used for beneficial purposes or treated as hazardous waste. The identified beneficial uses include predominantly brick and tile manufacturing. This study has successfully characterized the geological formations along the proposed alignment for the FCC tunnel. Analytical methods and schemes have been developed, tested and forecast the rocks to be encountered by proposed excavation machines and the beneficial uses for the excavated rock material.
|Translated title of the contribution||Geologische und multi-analytische Untersuchungen zur Vorhersage von Verwertungsszenarien für weiches, tonreiches Sedimentgestein für die zukünftige, unterirdische Infrastruktur des CERN im Genfer Becken (Schweiz-Frankreich)|
|Publication status||Published - 2022|
Bibliographical noteno embargo
- rock materials
- Geneva Basin