A specific value expressing the drilling properties of a rock in terms of the penetration rate with a certain type of bit and feed pressure.

To excavate horizontally or at an inclination, as in a drift, tunnel, adit, or entry. Distinguished from sink or raise.

Performing of underground space by means of drilling, blasting or by means of TBM

Underground space performed by driving technology without removing of overburden

A mechanical tunnelling shield having a cutting head mounted on a drum which revolves inside the outer skin of the shield, providing access to the tunnel face through the drum.

Usually a man-made area that can be dewatered for the repair of ships. A dry dock may also be a semi-submersible floating structure. Immersed tunnel elements are sometimes fabricated or repaired in dry docks. The term is also sometimes applied to a graving dock or casting basin.

When solid lagging is used in a supported tunnel, pea gravel or other material may be blown in between the lagging and the excavated surface to furnish support.

Shotcrete in which the mixing water is added at the nozzle.

A term used to describe a cell, particularly for supply or exhaust ventilation, or for utilities.

The ability of concrete or shotcrete to resist weathering action, chemical attack, abrasion, and other conditions of service.

Equipment designed to allow the elimination of dust in air.