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suction dredge[′sək·shən ‚drej]
a floating excavation machine that sucks the soil up from under the water in the form of a water-soil mixture (pulp or slurry) and transports it to a waste bank or the bed of an elevated structure. A distinction is made between dredges that move the pulp to shore through pipes and hopper dredges, which move the soil into their own dumping holds.
Suction dredges are widely used in dredging operations, as well as in hydraulic-engineering construction during the erection of earthen dams by the aggradation method, during the erection of levees and other types of embankments, and during the digging of canals and channels. Suction dredges were used for the earthen dams of all the major hydroelectric power stations built on the Volga, Kama, Dnieper, and Don rivers. They are sometimes also used successfully in mining for the extraction of sand and gravel mixtures and the stripping of mineral deposits. Suction dredges are highly efficient mechanical equipment for large-volume earthmoving work.
The suction of soil from under the water was first used in France in 1859. Suction dredges first appeared in Russia in 1874. The basic unit of a suction dredge is the soil pump. Mechanical or hydraulic scarifiers are used for intensive soilintake work; the latter type is used for light soils. Mechanical shredding scarifiers are the most common type.
During operation, the suction dredge is moved by winches providing continuous contact between the soil-intake device and the face. Suction dredge specifications range in capacity from 10 to 8,000 cu m of soil per hour; the working depth is 2–60 m; and the power of the electric motors is 10–10,000 kilowatts and higher. The displacement of hopper dredges exceeds 15,000 tons. The Netherlands leads in the building of suction dredges. The largest seagoing suction dredges are built in Japan. River suction dredges for construction and dredging work are built in the USSR.
REFERENCESShkundin, B. M. Zemlesosnye snariady. Moscow, 1968.
Karkovskii, I. I.Sudatekhnicheskogoflota. Leningrad, 1968.