What separates the support of mining open­ings from the support of similar civil engineering structures is the fact that mine openings have to survive large defonnations as a result of changing stress conditions induced by progressive mining. Steel fibers impart to concrete and shotcrete a high degree of ductility which not only allows the shotcrete and concrete linings to absorb important rock movements, but also to increase their bearing capacity by a redistribution of the loads.
The use of shotcrete for the support of under­ground excavations was pioneered by the civil engineering industry. In recent years, the mining industry ha,;; become a major user of shotcrete for underground support. The simultaneous working