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Tunnel Construction. Tunnels are dug in types of materials varying from soft clay to hard rock. The method of tunnel construction depends on such factors as the ground conditions, the ground water conditions, the length and diameter of the tunnel drive, the depth of the tunnel, the logistics of supporting the tunnel excavation, the final use and shape of the tunnel and appropriate risk management.
Culverts can be constructed of a variety of materials including cast-in-place or precast concrete (reinforced or non-reinforced), galvanized steel, aluminum, or plastic (typically high-density polyethylene). Two or more materials may be combined to form composite structures. For example, open-bottom corrugated steel structures are often built ...
Precast concrete is a construction product produced by casting concrete in a reusable mold or "form" which is then cured in a controlled environment, transported to the construction site and maneuvered into place; examples include precast beams, and wall panels, floors, roofs, and piles.
Logo of Eurocode 2 An example of a concrete structure. In the Eurocode series of European standards (EN) related to construction, Eurocode 2: Design of concrete structures (abbreviated EN 1992 or, informally, EC 2) specifies technical rules for the design of concrete, reinforced concrete and prestressed concrete structures, using the limit state design philosophy.
The excavation is protected by a layer of sprayed concrete, commonly referred to as shotcrete. Other support measures can include steel arches, rock bolts, and mesh. Technological developments in sprayed concrete technology have resulted in steel and polypropylene fibers being added to the concrete mix to improve lining strength.
An unreinforced concrete arch is technically a masonry arch that use only very small stones, that is the aggregate of the concrete, sand and gravel. Such an arch would not stand without mortar. Some modern bridges are built masonry style with precast concrete blocks, like Gladesville Bridge that has a span of 305 metres (1000 ft). These types ...
In situ: Formwork construction and pouring of concrete occur on site, then the slab is assembled (if required). [4] Precast: The slabs are made somewhere else and then brought to the site and assembled. [4] Pre-fabricated: The reinforcements are integrated into the slab while being manufactured, without needing to reinforce the assembly on site ...
The bridge, also known as the Natchez Trace Parkway Arches, is the first segmentally constructed concrete arch bridge in the United States. [2] The arches comprise 122 hollow box segments precast in nearby Franklin, each of which was about 9.8 ft (3.0 m) long and weighed between 29 and 45 short tons. [2]