| Term | Definition |
|---|---|
| Chuck tender |
Assistant to the driller. (Before the use of modern jibs, the driller's assistant had to help position the drill steel while starting the hole in the face; hence the term "chuck tender").
|
| Cill |
Usually the highest point of the floor on which or against which the gate rests, and over which elements must pass during removal from the fabrication facility.
|
| Circular tunnel |
A tunnel of circular cross section, generally made with a full circular shield or tunnel boring machine.
|
| Civil defense / protection |
Protection of the civilian population against the effects of bombs, fallout, and chemical releases
|
| Cleanup |
The operation of removing loose muck, water, and other material from a tunnel prior to concreting.
|
| Closed shield |
A shield modified for use in subaqueous tunnels in which the working pockets can be closed when "shoving blind".
|
| Closure Joint |
See Joint, closure.
|
| CO Limit |
Maximum admissible limit of pollution produced by Carbon Monoxide.
|
| CO, CO2 |
Carbon monoxide, carbon dioxide. Common pollutants monitored in urban areas. Work has been directed at understanding the total cost to society of the release of such pollutants
|
| Coeur d'Alene lagging | Lagging placed tightly between the webs of adjacent ribs. |
| Cofferdam |
A watertight enclosure from which the water is pumped to expose the excavation bottom and permit work to be performed there.
|
| Collar braces (spreaders) |
Horizontal compression members, usually timber, placed between adjacent steel rib or timber supports. Collar braces are set in line and tightened with tie rods. If they are made of steel or precast concrete, they need not be removed before pouring concrete lining.
|
| Commuter |
A person traveling to and from work
|
| Commuter rail |
A rail line designed principally to handle commuter trips
|
| Compensation grouting |
A system by which grout is injected into the ground above a tunnel and below man-made surface features. The intention is to reduce the effects of surface settlement caused by the tunnelling works.
|
| Competence of rock / ground |
A measure of its capacity to resist deformation under load
|
| Competent rock / ground |
Rock / ground that can stand for relatively long periods with no support or only minimal support when a tunnel is excavated through it.
|
| Compressed air |
Air supplied to the tunnel at greater than atmospheric pressure, either to operate pneumatic tools or to facilitate tunnelling in very soft or wet ground. See also high air or low air.
|
| Concession |
In general, the granting of a favor or a point during negotiations. In business terms, can represent a contract allowing the building and/or operation of a facility by another company.
|
| Concrete pump |
A pump that mechanically forces concrete through a pipe-line into forms. (One type of concrete placer).
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