The depth below the still-water surface of the deepest part of a floating body.

See disadvantage

The operation of excavating the trench for an immersed tunnel

A mined passageway or portion of a tunnel. In the latter sense, depending upon its location in the final tunnel cross section, it may be classified as a "crown drift", "side drift", "invert drift", etc.

A heavy drill for drilling nearly horizontal holes in the tunnel face. Drifters require support from jibs.

In reference to construction operations, the making of a relatively small circular hole in earth or rock with a cutting tool, while removing the cuttings by means of a circulating fluid. Distinguished from bore.

A method of desintegrating rock by drilling small diameter holes on a planned layout, packing these with explosives and then firing to a fixed program to shatter the rock in a desired form.

Movable frame on which drill positioners, jibs and drills are mounted.

In drill-and-blast tunnel construction, a rubber-tyred or track mounted movable frame with platforms to support men and drills.

Mechanical control for moving, rotating and controlling jibs.

A method of excavating rock by drilling small-diameter holes on a planned layout, packing these with explosives, and then firing to a fixed program to shatter the rock in a desired form. Distinguished from machine mining, mechanical excavation.

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.