Ready to learn the coolest tunnel, engineering and infrastructure vocabulary words so you can impress your friends and family? Great!
Bentonite – clay formed from volcanic ash which can absorb large amounts of water and expands to many times its normal volume. Used to retain the sides of excavations in wet, unstable soil.
Bore – construction method for tunnels which involves digging a tube-like passage through the earth. Usually refers to mountain tunneling.
Caisson – a pressurized, bell-shaped structure which allows construction fully under the water.
Cofferdam – a waterproof wall, open at the top, enclosing a construction area below the water level.
Conduit – pipe or liner used as a passage for other pipes or wires.
Course – in tunnels, the path of a tunnel. In masonry, one horizontal row of blocks.
Consolidation – soil stabilization.
Cross Section – the shape of a tunnel; shapes include ovoid, horseshoe, round or square.
Dewater – removal of water during construction.
Diaphragm Wall – watertight wall formed from cast-in-place reinforced concrete. Commonly uses slurry wall construction.
Drift – horizontal, underground passage.
Embedded Wall – retaining wall constructed using sections placed side-by-side or interlocking to form a continuous structure. Includes sheet pile, soldier pile, bored pile and diaphragm wall.
Full Face Boring Machine – a tunneling machine which has cutting teeth at its front. It creates the tunnel opening while passing the waste material through the rear. Many types of tunnel boring cut small sections which are progressively enlarged. A full face boring machine cuts the complete cross section of the tunnel at once.
Grade – the elevation of the ground surface. Often used to describe the angle or slope of the surface.
Gravity wall – retaining wall relying on significant mass, dimensions or modular sections. Little or no stability is gained from the natural resistance of the supported. soil. May be large stone blocks, pre-fabricated concrete modules, or reinforced construction with spread foundations. freezing or other methods.
Grouting – unstable rock and soil is strengthened by the injection of chemicals, cementitious grout.
Immersed Caisson – a pressurized, bell-shaped structure which allows construction fully under the water.
Immersed Tube – construction method using pre-fabricated tunnel sections. While the ends are sealed, it is lowered into position under the water and attached to other sections.
Lagging – boards placed side-by-side to retain the face of an excavation. Held in place by soldier piles.
Line – a description of the location and grade of a tunnel.
Lining – materials used to finish the inside surface of the tunnel. The initial supports and preliminary liner are placed as the tunnel is being excavated. These help stabilize the interior surface. Shotcrete may be sprayed on as a preliminary liner. Later, additional coatings may be applied or other types may be used such as prefabricated steel or concrete panels, rock bolting, steel ribs and wood lagging, or masonry. Waterproofing liners are also used.
Micro Tunneling – construction method for tunnels which are too small for humans to dig inside. May be performed using tethered, remote-controlled drilling machines or pipe jacking.
Muck – debris removed during excavation.
NATM (New Austrian Tunneling Method) – construction method, also known as the shotcrete method. As the excavation progresses, a layer of concrete is immediately sprayed on the interior surface of the tunnel and rock bolts are driven in. This method attempts to maintain the original rock structure by avoiding settling, subsidence and deformation. Additional liners may be added or more layers of shotcrete may be applied.
Pipe Roof Method – construction method in which steel pipes are laid along the sides and roof of the tunnel course and the tunnel was then constructed inside.
Reinforced Soil Wall – retaining wall using various methods of attaching strips, mesh or other reinforcements to an excavated face. Soil nails may be driven in to attach the reinforcements and added further stability.
Rock Bolts – steel bar with larger plates at its head. These are driven into the interior surface of the tunnel to stabilize and add strength to the rock. See soil nails.
Shaft – a vertical, underground passage.
Sheet Pile – pre-fabricated sections installed vertically side-by-side to form a retaining wall.
Shield – a metal frame used to maintain the opening as the tunnel boring progresses. As forward progress is made, the liner is constructed behind the shield, and the shield is jacked or moved forward.
Shotcrete – quick-setting concrete is sprayed onto the bare rock surface immediately after excavation. It forms preliminary tunnel liner.
Slurry Wall – construction method used in wet, unstable soil. As the trench is excavated, it is filled with bentonite slurry. This fluid mixture allows the excavation to continue while preventing the passage of groundwater or the collapse of the trench walls. The trench is later backfilled with other material, forms for poured concrete walls, or pre-fabricated wall sections.
Soil Nail – steel rod driven into the ground to stabilize soil. Used as part of a retaining wall and may be attached to reinforcing strips, mesh or other buried anchors (deadman). Also call a tieback.
Soldier Pile – steel H-shape beam driven vertically into the ground to provide supports for lagging.
Spile – rod driven into soft ground or unstable rock to provide stabilization. A grouted spile is one which is inserted into a pre-drilled hole, when is then back-filled with grout.
Sunken Tube – construction method using pre-fabricated tunnel sections. While the ends are sealed, it is lowered into position under the water and attached to other sections. Also immersed tube.
Tailings – in mining, waste material remaining after the valuable minerals have been extracted. Stored in piles or used as fill.
Tunnel – an underground passage for vehicles or pedestrians, especially one which is created by digging into earth. Occasionally, tunnel structures are built in an excavated area then covered over.
Tunnel Boring Machine (TBM) – a tunneling machine which has cutting teeth at its front. It creates the tunnel opening while passing the waste material through the rear.
Water Table – the underground elevation below which the earth is saturated with groundwater. Groundwater includes rainwater which has seeped below the surface or is supplied by aquifers, water-saturated layer of rock.