| Term | Definition |
|---|---|
| Sump |
Sumps (reservoirs) are provided at the portals and at low points (nadirs) to contain quantities of run-off and leakage water compatible with storage requirements of the pumps provided. Oil-water separators are usually required, and sumps within a tunnel most often discharge to portal sumps.
|
| Suspended Slab |
Slab provided to span across a cell above a space, such as ceiling and roadway slabs when ventilation ducts above or below the roadway are used.
|
| Sustainable development |
The type of overall development (economic, social, energetic, environmental, etc.) which makes it possible to meet the needs of the present generation without jeopardizing those of the future generations.
|
| Swell |
An increase in rock volume when it passes from the intact to the broken state
|
| Swelling |
Increase in volume upon exposure to water
|
| Swelling ground |
Material that expands in volume by absorbing or adsorbing water so that it tends to move into a tunnel opening or to exert great pressure upon the supports.
|
| Swing shift |
Shift that extends from 4:00 pm to midnight. See day shift.
|
| Tail void |
The annular space between the outer diameter of the shield and the outside of the primary lining.
|
| Tar coal |
Very used in tunnelling construction, it is very pollutant.
|
| Telecopic forms |
Full-circle or arch forms that, when stripped and collapsed, will pass through other forms that are erected in place.
|
| Temporary ballast |
Material used to temporarily increase the effective weight ot the tunnel or a tunnel element during the fabrication and installation phases until replaced by backfill or permanent ballast. The material may be solid or liquid
|
| Temporary support |
Essentially the same as initial support, except that the elements can be (and sometimes must be) removed because on non-contribution to or incompatibility with the final lining.
|
| Terminal structure |
The non-immersed structure abutting the first and last immersed tunnel elements
|
| The Planning & Building Act (Sweden) |
The principal act for regulating physical planning and building development
|
| Thermal comfort |
Personal comfort related to such thermally important factors as temperature, humidity, air flow, etc
|
| Thin-stream conveying |
A method of pneumatic conveyance from the shotcrete machine by which either dry mix or wet mix is conveyed through the delivery line by compressed air.
|
| Three-dimensional ownership |
The possibility to own three-dimensional space i.e. real estate not only delimited in two dimensions but also by depth
|
| Tie rods |
Tension members between sets to maintain spacing. These pull the sets against the struts.
|
| Tight |
Projection of rocks in a tunnel past the "A line".
|
| Tilmeter |
A device for precisely measuring rotation, or chage in orientation, at a specific location on a structure or the ground surface.
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