11. Glossary

Shield

All the components inside the cylindrical steel casing used to excavate the tunnel.

Back-up or trailing train trailers

Set of trailers behind the shield to extend the servitudes and supply the shield with consumables.

TBM (Tunnel Boring Machine)

Shield and undercarriage assembly.

Marin or pickling

All excavated material plus excavation consumables such as surfactants, polymers, natural fines or bentonite.