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|Title:||Study and evaluation of remedial sand bypassing procedures|
|Authors:||Scripps Institution of Oceanography.|
Harris, Rolland W.
Inman, Douglas L. (Douglas Lamar), 1920-
Bailard, James Alan, 1950-
Oda, Ronald L.
|Publisher:||Hydraulics Laboratory (U.S.)|
Engineer Research and Development Center (U.S.)
|Series/Report no.:||Contract report (U.S. Army Engineer Waterways Experiment Station) ; H-76-1.|
Abstract: Millions of dollars are spent annually for dredging harbor entrances in the United States. Many attempts have been made in the past to optimize these dredging costs by designing jetties to trap sand and to provide calm water for the dredges. This approach has not reduced the annual quantities to be dredged. The purpose of this program was to investigate and develop a practical method for the management of sand influenced by littoral transport. The work covered laboratory research, field investigations, and tests. Initially, laboratory investigations of jet pumps, crater-sinks, and fluidization were conducted utilizing specially designed apparatus. During the laboratory investigations a new principle of fluidization was developed. This new form of fluidization is called "duct-flow" fluidization. Duct-flow, when used in conjunction with the crater-sink principle, greatly expands the scope of sand management systems. Field tests of craters dredged on the ocean floor showed that wave action causes the crater to elongate in a direction parallel to the wave crests. The result is an eliptical shaped crater. Field and laboratory tests of duct-flow show that the bulk volume flow rate of sand from the fluidizer is proportional to the drive-water flow rate. The dimensions of a prototype duct-flow system appear to be almost unlimited. Later, the jet pump and fluidization apparatus were operated individually in the field. Finally, a prototype field sand bypassing system consisting of a fluidizer intercepting littoral drift on a sand spit was used to feed a crater. Sand was removed by a jet pump and deposited on shore 89 meters away. Aerial photographs were taken, and beach profiles, crater, and fluidized trench were measured throughout the field tests. The field tests demonstrated that the prototype system effectively intercepted littoral drift, in spite of the deliberately adverse conditions established by the investigators.
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