| Term | Definition |
|---|---|
| Tunnelling cycle |
In rock tunnelling, the 6-part excavation cycle is drilling holes for explosives, loading, blasting (shooting), ventilating, mucking, and erecting supports.
|
| Tunnelling machine |
A continuously excavating machine utilizing one or more rotating cutterheads which are revolved under pressure against the tunnel face. Full-face or part-face excavator
|
| Tunnelling machine |
A continuous excavating machine utilizing one or more rotating cutterheads which are revolved under force against the tunnel face.
|
| Underground |
Below ground level
|
| Underground parking |
Parking spaces or structures principally below ground level. Ventilation provisions are important compared to aboveground parking
|
| Underground planning |
Planning activity aiming to divide subsurface for human activities according to the ecological, economical and technical point of view
|
| Underground space |
Space created or used underground
|
| Underpass |
A structure, including its approaches which allows one road to pass under another road (or an obstacle)
|
| Unit |
Term sometimes used to refer to an element.
|
| User |
A person who uses a system for their own needs rather than one than operates it or observes its operation
|
| V cut |
Inclined short drill holes near the center of the tunnel face, drilled so that when the first shots are exploded in the round, a wedge of rock is removed, which allows relief for the remaining rock when the delay exploders set off the charges in the other drill holes.
|
| Value |
Maximum price that would be paid to obtain a good. It is generally a function of the quantity of this good already possessed or already consumed
|
| Value of life |
A monetary value assigned to loss of life for use in comparative analyses of the cost effectiveness of design options with different safety implications
|
| Value of time |
A monetary value assigned to time saved or lost by users of a transportation system. This may be calculated to vary by anticipated user or user activity when delayed, e.g. business use versus recreational use
|
| Vent line |
Large-diameter pipe used to furnished fresh air or exhaust polluted air from an underground opening
|
| Ventilation |
The provision of air circulation/fresh air to an enclosed space. This can provide cost implications when comparing underground and surface solutions
|
| Ventilation (longitudinal ventilation) |
A system in which fresh air is supplied at one end of the tunnel and the polluted air is expelled at the other
|
| Ventilation (semi-transverse ventilation) |
A system in which a separate ventilation duct is used for the supply of fresh air through many supply vents along the tunnel. The polluted air is discharged through the end of the tunnel. Also used to describe a system where fresh air is supplied from the end of the tunnel and polluted air is drawn out over the length of the tunnel by exhaust fans
|
| Ventilation (transverse ventilation) |
A system in which separate supply and exhaust duct systems are used, so that fresh air is distributed and polluted is collected over the length of the tunnel by supply and exhaust fans
|
| Ventilation duct |
Pipeline used to ventilate the tunnel, eliminating polluted air.
|
