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Caisson (engineering)
In geotechnical engineering, a caisson ( or ; borrowed from French ''caisson'', from Italian ''cassone'', meaning ''large box'', an augmentative of ''cassa'') is a watertight retaining structure used, for example, to work on the foundations of a bridge pier, for the construction of a concrete dam, or for the repair of ships. Caissons are constructed in such a way that the water can be pumped out, keeping the work environment dry. When piers are being built using an open caisson, and it is not practical to reach suitable soil, friction pilings may be driven to form a suitable sub-foundation. These piles are connected by a foundation pad upon which the column pier is erected. Caisson engineering has been used at least since the 18th century, and was notably used in the construction of the Brooklyn Bridge, which was completed in 1883. Types To install a caisson in place, it is brought down through soft mud until a suitable foundation material is encountered. While bedrock is pref ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Caisson Schematic
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Caisson (French for "box") may refer to: * Caisson (Asian architecture), a spider web ceiling * Caisson (engineering), a sealed underwater structure * Caisson (lock gate), a gate for a dock or lock, constructed as a floating caisson * Caisson (pen name), of Edward Sperling * Caisson (western architecture), a type of coffer * Caisson disease, or decompression sickness * Caisson lock, a type of canal lock * Deep foundation, also called a caisson foundation * Limbers and caissons, a two-wheeled cart for carrying ammunition, also used in certain state and military funerals See also * Kazon, a fictional alien race in ''Star Trek'' * Khe Sanh Khe Sanh is the district capital of Hướng Hoá District, Quảng Trị Province, Vietnam, located 63 km west of Đông Hà. During the Vietnam War, the Khe Sanh Combat Base was located to the north of the city. The Battle of Khe San ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sandhogs
Sandhog is the slang term given to urban miners and construction workers who work underground on a variety of excavation projects in New York City, and later other cities. Generally these projects involve tunneling, caisson excavation, road building, or some other type of underground construction or mining projects. The miners work with a variety of tools including using tunnel boring machines and explosives to remove material for the project they are building. The term sandhog is an American colloquialism. Starting with their first job in 1872, the Brooklyn Bridge, the "hogs" have built a large part of the New York City infrastructure including the subway tunnels and sewers, Water Tunnels No. 1 and No. 2 as well as the currently under construction Water Tunnel No. 3, the Lincoln, Holland, Queens-Midtown, and Brooklyn-Battery tunnels. In addition, they worked on the foundations for most of the bridges and many of the skyscrapers in the city. Traditionally, these workers have ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boat Lift
A boat lift, ship lift, or lift lock is a machine for transporting boats between water at two different elevations, and is an alternative to the canal lock. It may be vertically moving, like the Anderton boat lift in England, rotational, like the Falkirk Wheel in Scotland, or operate on an inclined plane, like the Ronquières inclined plane in Belgium. History A precursor to the canal boat lift, able to move full-sized canal boats, was the tub boat lift used in mining, able to raise and lower the 2.5 ton tub boats then in use. An experimental system was in use on the Churprinz mining canal in Halsbrücke near Dresden. It lifted boats using a moveable hoist rather than caissons. The lift operated between 1789 and 1868,Charles Hadfield ''World Canals: Inland Navigation Past and Present'', p. 71, and for a period of time after its opening engineer James Green reporting that five had been built between 1796 and 1830. He credited the invention to Dr James Anderson of Edinburgh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Caisson Lock
The caisson lock is a type of canal lock in which a narrowboat is floated into a sealed watertight box and raised or lowered between two different canal water levels. It was invented in the late 18th century as a solution to the problem posed by the excessive demand for water when conventional locks were used to raise and lower canal boats through large height differences. Such locks, each of which would only raise and lower boats through small height differences of a few feet, would not suffice when large height differences had to be tackled nor when water was in short supply. The caisson (or ) was thought to be one solution, although it transpired that the technology of the day was not capable of achieving this type of construction economically. It was designed primarily as a water-saving measure, and also was an attempt to minimise construction costs compared with other engineering solutions of the time. In use it was capable of replacing up to seven conventional locks. Othe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Synonym
A synonym is a word, morpheme, or phrase that means exactly or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are all synonyms of one another: they are ''synonymous''. The standard test for synonymy is substitution: one form can be replaced by another in a sentence without changing its meaning. Words are considered synonymous in only one particular sense: for example, ''long'' and ''extended'' in the context ''long time'' or ''extended time'' are synonymous, but ''long'' cannot be used in the phrase ''extended family''. Synonyms with exactly the same meaning share a seme or denotational sememe, whereas those with inexactly similar meanings share a broader denotational or connotational sememe and thus overlap within a semantic field. The former are sometimes called cognitive synonyms and the latter, near-synonyms, plesionyms or poecilonyms. Lexicograph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Invasion Of Normandy
Operation Overlord was the codename for the Battle of Normandy, the Allied operation that launched the successful invasion of German-occupied Western Europe during World War II. The operation was launched on 6 June 1944 (D-Day) with the Normandy landings. A 1,200-plane airborne assault preceded an amphibious assault involving more than 5,000 vessels. Nearly 160,000 troops crossed the English Channel on 6 June, and more than two million Allied troops were in France by the end of August. The decision to undertake a cross-channel invasion in 1944 was taken at the Trident Conference in Washington in May 1943. General Dwight D. Eisenhower was appointed commander of Supreme Headquarters Allied Expeditionary Force, and General Bernard Montgomery was named commander of the 21st Army Group, which comprised all the land forces involved in the invasion. The coast of Normandy of northwestern France was chosen as the site of the invasion, with the Americans assigned to land at sectors ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phoenix Breakwaters
The Phoenix breakwaters were a set of reinforced concrete caissons built as part of the artificial Mulberry harbours that were assembled as part of the preparations for the Normandy landings during World War II. They were constructed by civil engineering contractors around the coast of Britain. They were collected at Dungeness and Selsey, and then towed by tugboats across the English Channel and sunk to form the Mulberry harbour breakwaters replacing the initial " Gooseberry" block ships. Caissons were added in the autumn of 1944 to reinforce the existing structure to cope with the harbour continuing in use longer than planned. Several Phoenix breakwaters still exist in Britain: two are part of the harbour off Castletown at Portland Harbour in Dorset, and two can be dived in less than 10 metres of water off Pagham in West Sussex. There is also a smaller Phoenix Caisson (type C) in Langstone Harbour in Hampshire. A wrecked Phoenix breakwater is also to be seen, broken in two, in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elevator
An elevator or lift is a wire rope, cable-assisted, hydraulic cylinder-assisted, or roller-track assisted machine that vertically transports people or freight between floors, levels, or deck (building), decks of a building, watercraft, vessel, or other structure. They are typically powered by electric motors that drive traction cables and counterweight systems such as a hoist (device), hoist, although some pump hydraulic fluid to raise a cylindrical piston like a hydraulic jack, jack. In agriculture and manufacturing, an elevator is any type of conveyor device used to lift materials in a continuous stream into bins or silos. Several types exist, such as the chain and bucket elevator, grain auger screw conveyor using the principle of Archimedes' screw, or the chain and paddles or forks of hay elevators. Languages other than English, such as Japanese, may refer to elevators by loanwords based on either ''elevator'' or ''lift''. Due to wheelchair access laws, elevators are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dysbaric Osteonecrosis
Dysbaric osteonecrosis or DON is a form of avascular necrosis where there is death of a portion of the bone that is thought to be caused by nitrogen embolism (blockage of the blood vessels by a bubble of nitrogen coming out of solution) in divers. Although the definitive pathologic process is poorly understood, there are several hypotheses: *Intra- or extravascular nitrogen in bones, "nitrogen embolism". *Osmotic gas effects due to intramedullary pressure effects. *fat embolism *hemoconcentration and increased coagulability. Presentation The lesion begins as a localised area of infarction, usually without symptoms. Early identification of lesions by radiography is not possible, but over time areas of radiographic opacity develop in association with the damaged bone. Symptomatic lesions usually involve joint surfaces, and fracture where attempted healing occurs. This process takes place over months to years and eventually causes disabling arthritis, particularly of the femoral head ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barotrauma
Barotrauma is physical damage to body tissues caused by a difference in pressure between a gas space inside, or contact with, the body and the surrounding gas or liquid. The initial damage is usually due to over-stretching the tissues in tension or shear, either directly by an expansion of the gas in the closed space or by pressure difference hydrostatically transmitted through the tissue. Tissue rupture may be complicated by the introduction of gas into the local tissue or circulation through the initial trauma site, which can cause blockage of circulation at distant sites or interfere with the normal function of an organ by its presence. Barotrauma generally manifests as sinus or middle ear effects, lung overpressure injuries and injuries resulting from external squeezes. Decompression sickness is indirectly caused by ambient pressure reduction, and tissue damage is caused directly and indirectly by gas bubbles. However, these bubbles form out of supersaturated solution from ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Decompression Sickness
Decompression sickness (abbreviated DCS; also called divers' disease, the bends, aerobullosis, and caisson disease) is a medical condition caused by dissolved gases emerging from solution as bubbles inside the body tissues during decompression. DCS most commonly occurs during or soon after a decompression ascent from underwater diving, but can also result from other causes of depressurisation, such as emerging from a caisson, decompression from saturation, flying in an unpressurised aircraft at high altitude, and extravehicular activity from spacecraft. DCS and arterial gas embolism are collectively referred to as decompression illness. Since bubbles can form in or migrate to any part of the body, DCS can produce many symptoms, and its effects may vary from joint pain and rashes to paralysis and death. DCS often causes air bubbles to settle in major joints like knees or elbows, causing individuals to bend over in excruciating pain, hence its common name, the bends. Individu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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