A person traveling on foot

The optimum speed with which a drill or excavator can advance through the ground in a short time before it is slowed or stopped by mechanical breakdown, ground instability, or the like.

Two perforated half round sections of sheet metal which are filled with grout, wired together, and installed in a hole. A steel bar with a rounded nose is forced inside the aleeve, causing the grout to squeeze through the perforations and bond to the sides of the hole.

Non-structural solid material placed inside or outside an immersed tunnel to increase its effective weight permanently

Issues pertaining to health or the functioning of living things

A small tunnel excavated over the entire length or over part of a larger tunnel, to explore ground conditions and/or to assist in final excavation. May also be referred to as "pilot drift".

Traveling support for the discharge line from a concrete placer.

Excavating a tunnel under air pressure.

See forepoling

Interference with a natural system that is potentially harmful or unwanted

An overstressed rock condition involving the spontaneous and violent detachment of rock slabs. See also rock burst.

The structure or the end of the structure at the two ends of a tunnel at the interface of the covered and open sections

The entrance from the ground surface to a tunnel.

To start the tunnel excavation at the portal face.

The vertical members of a steel rib or timber support system.

A steel pressure vessel used for transporting concrete. At the point of placement, the concrete is ejected from the pot by use of compressed air.

Number of pounds of powder per cubic yard of rock.

Slang for man who handles explosives.

Pre- bagged concrete or shotcrete mix supplied in bags with all ingredients oven-dried and pre-mixed

A technique of inducing cracks roughly following the periphery of the rock shape to be excavated by the use of closely spaced holes and reduced explosive charges prior to main blasting; a subdivision of smooth blasting.