IPC Subgroup
E21D 13/02 Methods
Introduced: September 1968
Last revised: January 2006
Full Title
Large underground chambers; Methods or apparatus for making them > Methods
Classification Context
- Section:
- FIXED CONSTRUCTIONS
- Class:
- EARTH OR ROCK DRILLING; MINING
- Subclass:
- SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS