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Hudson's equation, also known as Hudson's formula, is an equation used by coastal engineers to calculate the minimum size of riprap (rock armour blocks) required to provide ''satisfactory'' stability characteristics for rubble structures such as breakwaters under attack from storm wave conditions. The equation was developed by the United States Army Corps of Engineers, Waterways Experiment Station (WES), following extensive investigations by Hudson (1953, 1959, 1961a, 1961b) (see Shore Protection Manual and Rock Manual referenced below). ==Initial equation== The equation itself is: : where: *''W'' is the design weight of the riprap armour (Newton) *'''' is the specific weight of the armour blocks (N/m3) *''H'' is the design wave height at the toe of the structure (m) *''K''''D'' is a dimensionless stability coefficient, deduced from laboratory experiments for different kinds of armour blocks and for very small damage (a few blocks removed from the armour layer) (-): : * ''K''''D'' = around 3 for natural quarry rock : * ''K''''D'' = around 10 for artificial interlocking concrete blocks *''Δ'' is the dimensionless relative buoyant density of rock, i.e. ''(ρr / ρw - 1)'' = around 1.58 for granite in sea water *''ρ''''r'' and ''ρ''''w'' are the densities of rock and (sea)water (-) *''θ'' is the angle of revetment with the horizontal 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Hudson's equation」の詳細全文を読む スポンサード リンク
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