| Term | Definition |
|---|---|
| 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.
|
| Toll |
Price paid for access to a highway facility
|
| Top heading |
The upper portion of a tunnel, often extending from springline to crown, pre-excavated in order to install arch support before opening the tunnel to full size.
|
| Top heading construction |
A tunnelling method in which a complete top heading is excavated end-to-end before excavation of the lower bench is begun. Distinguished from heading-and-bench construction.
|
| Top-down construction |
Underground construction system in which the ground slab is finished quickly and construction continues below this slab to finish the underground structure. This can allow a quick return of the surface to a needed use or a shorter overall building time.
|
| Towing or Transportation |
Several phases of construction of immersed tunnels may involve towing. The main tow is to the location where outfitting for immersion is to be done, usually close to the immersion point. The final tow it to the immersion point.
|
| Track |
The rail structure providing a single line of railway operation
|
| Traffic |
Coming or going of persons or goods
|
