Author(s): Hiroki Natumoto; Kanji Imai; Tukasa Koike
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Keywords: No Keywords
Abstract: The prediction of scour phenomenon is very difficult in perforning,becausethere are many influential factors involved such as flow condition,grain sizeand dimenslons of structure.Particularly,the formation of three-dimenslonalvortex system as well as the accerelation of fluid velocity around structuremake the scour phenomenon more complex.Traditionally speaking,in order todesign an effective anti-scour protection method,an experimental procedurehas to be employed in laboratory based on a relatively simple FroudeSimilarity Law.However,it might be considered that the limitation and theaccuracy of such experimental procedure is not fully understood at present,Just because the cost of the corresponding site experiment becomes soexpensive. This is particuralily true when the dimension of site modelbecomes large.Fortunately,the present authors had an opportunity to perform4large scale site experiment on scour through actually constructing largebridge foundations for a suspension bridge called Akashi-0hashi(the largestsuspension bridge when it is accomplished,its main span length 1990m). Aconcrete made circular cylinder with Its diameter 15m and its height 30m isused as a representative structural model in site.The cylinder is placed inwater depth 47m so that the top of the cylinder is submerged in water. Thescour depth,and extent as well as its speed observed in site are summarizedand they are compared with the corresponding laboratory test results. Somenew findings on scour similarity relation will be.presented in thisinvestigation.
Year: 1991