ABSTRACT
Shafts are vital access ways for many underground mines. They provide passageways for personnel, materials, and ventilation air. Vertical shafts are the norm, but inclines are also used. Shafts must be engineered for a long, stable design life; they must be safe at all points along the shaft route. Where the rock mass is strong and the in situ stress is low, an unlined shaft may be acceptable, for example, a ventilation shaft, but usually some provision is needed for preventing loose rock from cascading down the shaft. Even small rock fragments can do great harm after falling from considerable height. Rock bolts, steel strapping, wire mesh, screen of some type, lacing, and lagging are commonly used to prevent minor falls of rock in shafts and are usually installed during shaft sinking. A relatively thin concrete liner serves the same purpose and also provides a smooth surface that reduces air friction loss in ventilation shafts.
