Bridge Pressure Flow Scour at Clear Water Threshold Condition

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摘要 Bridgepressureflowscouratclearwaterthresholdconditionisstudiedtheoreticallyandexperimentally.Theflumeexperimentsrevealthatthemeasuredscourprofilesunderabridgearemoreorless2-dimensional;allthemeasuredscourprofilescanbedescribedbytwosimilarityequations,wherethehorizontaldistanceisscaledbythedeckwidthwhilethelocalscourbythemaximumscourdepth;themaximumscourpositionislocatedjustunderthebridgeabout15%deckwidthfromthedownstreamdeckedge;thescourbeginsataboutonedeckwidthupstreamthebridgewhilethedepositionoccursatabout2.5deckwidthsdownstreamthebridge;andthemaximumscourdepthdecreaseswithincreas-ingsedimentsize,butincreaseswithdeckinundation.Thetheoreticalanalysisshowsthat:bridgescourcanbedividedintothreecases,i.e.downstreamunsubmerged,partiallysubmerged,andtotallysubmerged.Fordownstreamunsubmergedflows,themaximumbridgescourdepthisanopen-channelproblemwheretheconventionalmethodsintermsofcriticalvelocityorbedshearstresscanbeapplied;forpartiallyandtotallysubmergedflows,theequilibriummaximumscourdepthcanbedescribedbyascourandaninundationsimilaritynumber,whichhasbeenconfirmedbyexperimentswithtwodecksandtwosedimentsizes.Forapplication,adesignandfieldevaluationprocedurewithexamplesispresented,includingthemaximumscourdepthandscourprofile.
机构地区 不详
出版日期 2009年02月12日(中国期刊网平台首次上网日期,不代表论文的发表时间)
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