| Term | Definition |
|---|---|
| Rackers |
Support timbers placed at an angle.
|
| Raise |
To excavate a shaft upwards, in distinction from sinking.
|
| Raise |
A vertical or inclined shaft driven upward from an underground opening, most frequently to connect with another underground opening or the surface.
|
| Raise bore and ream |
To raise bore a shaft of moderate size, then enlarge to a greater diameter by pushing or pulling a mechanical "reaming" device through the initial opening.
|
| Raise bore and slash |
To raise bore a shaft of moderate size, then enlarge to a greater diameter by means of blasting, or "slashing".
|
| Raise boring |
To raise a shaft by means of a rotating mechanical devise generally powered and/or guided upward by a drill stem fed through a small down-drilled pilot hole.
|
| Ravelling ground |
Poorly consolidated or cemented materials that can stand up for several minutes to several hours at a fresh cut, but then start to slough, slake, or scale off.
|
| Ready-mix concrete or shotcrete |
Concrete or shotcrete ingredients mixed by a concrete batch plant and delivered to the site in ready-mix trucks ready for placing or shooting
|
| Rebound |
Shotcrete material which ricochets off the receiving surface. Loose material from the shotcreting process which has not adhered to the excavated surface nor the panel of shotcrete being formed. It can provide planes or zones of weakness in the shotcrete lining if it sets, is not cleared away and is subsequently incorporated into later panels.
|
| Recycling |
The reuse or remanufacture of items to reduce waste and/or lower costs
|
| Regional rail |
A rail system designed to serve a region rather than a city
|
| Replacement value |
The current cost of replacing an object or system with one of at least similar functionality or desired attributes
|
| Residual soil |
Soil polluted or altered after a procedure.
|
| Return | Concept which expresses the comparison of the benefits and the costs of a project. This concept is not limited necessarily to financial benefits. |
| Ribs |
Curved steel supports, usually cold-rolled or pressed structural beams made to conform to the required shape. H-beams or wide flange beams are preferable to I-Bemas, as wider flanges provide more surface for blocking and lagging, and the section has greater resistance to twisting. (H = heavy ribs, M = medium ribs).
|
| Ribs and lagging |
Elements that make up a primary lining consisting of steel ribs and wood or steel lagging
|
| Rift, grain and hardway |
Terms common in quarrying, indicating the three orthogonal directions of preferred splitting within massive, quartz-bearing, igneous rock. The rift is the direction of easiest splitting and is usually horizontal or nearly so. The grain, usually perpendicular to the rift, is the direction of next easiest splitting. The hardway (or headgrain) is the plane of most difficult splitting among the three directions. In hard rock tunnelling, if the hardway direction is normal to tunnel advance, considerable powder is required for removal.
|
| Rigging |
A system of lines, winches and hoists used to control the position of an element, both horizontally and vertically, especially during immersion. Lines may be attached indirectly to the shore, anchors, pontoons, derrick barges or other lowering equipment.
|
| Right-of-way |
A legal right for movement of people or goods. Also, the land area that provides this
|
| Risk |
A combination of the probability and the degree of the possible injury or damage to health in a hazardous situation.
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