With drill-filling piles, concrete is poured into a drilled shaft. In special cases, such as tower structures, threaded steel piles are used. Concrete tubular piles 1,000–3,000 mm in diameter and 6–12 m long are also used. Reinforced-concrete piles can also be round and hollow (diameter 400–800 mm, length 4–12 m). They may be solid with transverse reinforcement (3–20 m long) or solid without transverse reinforcement (3–12 m), or they may contain a cylindrical hole (3–8 m). Reinforced-concrete driven piles usually have a square cross section. Driven piles of reinforced concrete are most common in the USSR, accounting for more than 90 percent of the piles in use in 1973. Drill-filling piles are made of concrete or reinforced concrete and are cast in place. Driven piles are prefabricated of reinforced concrete, steel, or wood and are driven into the soil by pile drivers, vibratory pile drivers, or vibratory jacking drivers. Piles are classified according to methods of piling. In addition to piles used in foundations, sheet piles, chiefly of metal, are also used in sheet-pile walls to form, for example, temporary fencing in the excavation of foundations or cofferdams in certain hydraulic-engineering installations. In most cases, piles are used in pile foundations, where they transfer a load from the structure to the soil. More recently, high-powered ultrasonic vibrators have come into use for driving piles.Ī structural unit (pole or balk) that is completely or partially introduced into the ground. Pilings are driven into the ground by pile drivers using drop hammers, diesel hammers, steam hammers, or compressed-air hammers. Sheet piling consists of wooden boards or interlocking steel plates and is used largely as a cofferdam to keep water from structural work, piers, and buildings. One method consists of driving a steel shell into the ground and filling it with concrete, after which the shell is withdrawn and the molded concrete is in place. Only in such subsurfaces can the water-jet system be employed. The steel is not needed when the piles are set by the force of jets of water in this method an iron pipe is set in the center of the pile, and water under pressure is sent down to wash away the sand, silt, or soft earth that it is to displace. Precast piles are made of concrete reinforced with steel bars looped one to the other and are tipped and topped with protective steel when driven into the ground. They are very strong and durable, do not deteriorate when wholly in the ground, and are immune to the attacks of boring insects. Concrete piles are generally of two types, the precast and the cast-in-place. Their length is usually 20 to 60 ft (6.1–18.3 m), and they are generally spaced 3 or 4 ft (.9 or 1.2 m) apart from center to center. They are shaped for driving and sometimes have a pointed iron shoe set on the sharp end, with the butt end encircled by an iron band to prevent brooming under the blows of the pile driver. Wooden piles last a very long time underwater but are subject to decay when buried underground. (25.4 cm) thick at the butt, are used in foundations for houses. Slender tree trunks, roughly trimmed and about 10 in. Vertical piles, or bearing piles, the most common form, are generally needed for the foundations of bridges, docks, piers, and buildings. Pile, post of timber, steel, or concrete used to support a structure.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |