Classifications

• • E—FIXED CONSTRUCTIONS
  • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
  • E02F—DREDGING; SOIL-SHIFTING
  • E02F3/00—Dredgers; Soil-shifting machines
  • E02F3/04—Dredgers; Soil-shifting machines mechanically-driven
  • E02F3/88—Dredgers; Soil-shifting machines mechanically-driven with arrangements acting by a sucking or forcing effect, e.g. suction dredgers
  • E02F3/90—Component parts, e.g. arrangement or adaptation of pumps
  • E02F3/92—Digging elements, e.g. suction heads
  • E02F3/9287—Vibrating suction heads

Definitions

• the invention relates to a method and an apparatus for removing sandy / silty deposits on ground surfaces of waters by means of hydropneumatic measures.
• Suction dredger methods are suitable for all types of deposits and are variously described above.
• Popular today are those methods in which the sucked mixture of solid and liquid components is partially separated, so that a portion of the sucked water can be returned to the water (Suction Hopper Dredging).
• Dredging with the water injection device (WI method) and the hopper dredger reach the limits of their performance especially in sandy / low silty sediments, with a linear grain distribution (especially of the sand fraction).
• sandy / silty in the context of this description is meant the presence of sand together with clay particles.
• a method for better mobilization of fine-grained, sandy and / or silty sediments in bodies of water during the rearrangement, which makes use of the thixotropic properties of such sediments.
• thixotropy refers to a state in fine-grained, mostly sandy / clayey sediments in which reversible viscosity differences occur due to mechanical stress. Typical is a change from solid to liquid by vibration with subsequent return to the solid state. Crucial for these properties are grain size composition and type of sediment forming substances. Usually it is platelet-shaped clay minerals, which - against a microscopic scale - are initially supported against each other in all spatial directions. When shocked, the structure collapses like a house of cards, the mineral platelets are paralleled and begin to slip past each other under the influence of gravity due to the lack of internal adhesive forces. Thixotropy has also been observed with aqueous fine sands (quicksand).
• the Reynolds number provides information about the flow state. Physically important is the boundary layer analysis of the solid-liquid phase. Within longitudinally flown walls (particle walls), strong frictional forces act in a very thin layer, the boundary layer or the friction layer.
• K R ⁇ x F x dv / dz N
• the boundary layer thickness is essential for the frictional forces that must be expended when transporting the sediments. Due to the nature of the mechanical influence on the thixotropic state of the sediments, according to the invention, the K R is at times substantially reduced in size.
• the kinematic and dynamic viscosity of the semi-stable sediment is significantly reduced in the short term by targeted mechanical forces acting on the thixotropic medium before the hydropneumatic action by the aforementioned dredging method on the sediment.
• the mechanical force is preferably applied by shearing and shaking on the sediment surface.
• a resonance is sought in the relocated sediments. The optimal parameters can be easily determined by preliminary tests.
• the technical device for reducing the viscosity is preferably installed on water injection dredgers, hopper dredgers and tractors. It consists of, for example, a beam-like lowerable device, which is up to 12 m long and is carried across the direction of travel of the ships on the sediment base lying. Through this device, the mechanical energy is transmitted via vibrators, shaving heads, vibrators and eccentrics to the thixotropic sediment.
• the respective use of the aforementioned various devices depends on the sediment quality to be processed and is selected according to the best efficiency.
• the device is z. B. in the water injection process in the machine direction, and approximately parallel to the water injection bar and reduces the viscosity. Hydrodynamics is used to transfer the sediment into a density stream via the following injection nozzles, which is then transferred to the flow or slope.
• Impact number term from physical chemistry; a mathematical formula by which the frequency of two or more chemical reactants can be calculated.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Mining & Mineral Resources (AREA)
• Civil Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Structural Engineering (AREA)
• Treatment Of Sludge (AREA)

Priority Applications (3)

Applications Claiming Priority (1)

Publications (1)

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ID=44201175

Family Applications (2)

Family Applications After (1)

Country Status (2)

Cited By (1)

Citations (4)

• 2011
  • 2011-02-08 EP EP11153674A patent/EP2484838A1/fr not_active Withdrawn
• 2012
  • 2012-02-01 EP EP12703693.7A patent/EP2683878A1/fr not_active Withdrawn
  • 2012-02-01 WO PCT/EP2012/000449 patent/WO2012107180A1/fr active Application Filing

Patent Citations (4)

Non-Patent Citations (1)

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