黃河下游游蕩性河段浮橋建設對河勢及防洪的影響分析

黃河下游游蕩性河段浮橋建設對河勢及防洪的影響分析第1頁/共31頁Backgroundofthestudy

項目研究背景

2.BriefIntroductionofFenkaifloatBridge

封開浮橋簡介

3.AnalysisofEffectofFloatBridgeConstructiononFlowCondition

浮橋建設對水流條件影響的分析

4.AnalysisofPossibleEffectofFloatBridgeonRiverRegimeChanges

浮橋建設對河勢的可能影響分析

5.ConclusionsandSuggestions

結論和建議

OutlineofthePresentation第2頁/共31頁

MoreandmorefloatbridgeshavingbeenbuiltonthelowerYellowRiverduetoEconomicdevelopmentSofar,53bridgesinShandongProvinceSince2000,floatbridgehasgraduallymovedtotheupperwanderingreachesoftheLowerYellowRiver.1.Backgroundofthestudy第3頁/共31頁CeaselessgoingonofabnormalriverregimenearsomefloatbridgesmakepeoplepaymoreattentiontotheeffectoffloatbridgeontheriverregimesStudyingthechangeinwaterflowandriverregime,andthepossibleeffectonfloodcontrolcanprovidepositiveandscientificbasisforthefuturefloatbridgeconstructionRiverregimeevolutionofDagongtowang’anreachfrom2004to2006Abnormalriverregime1.Backgroundofthestudy第4頁/共31頁2.BriefIntroductionoftheFeng-KaiYellowRiverFloatBridgeFeb.2003begantobebuiltMar.2004opentotraffic.Thechannelofthereachwherethebridgeislocatedis690mwide,andthemainflowis4mdeepinaverageThefloatbridgeis880mlongintotalandrunsoverthenewfloodplainandthemainchannel,andiscomposedof44sections

Thebodyofthebearingboatofthebridgeis21.38mlong,andsingleboatlengthis4.3mRouteofFengkaiFloatbridgeFengqiucountyofXinxiangcityKaifengcountyofKaifengcity第5頁/共31頁3.AnalysisofEffectofFloatBridgeConstructiononFlowConditionTheflowconditionchangeswillbeanalyzedforfourflowratemagnitudes(500m3/s,1000m3/s,2000m3/sand4000m3/s).FlowConditionPriortoFloatBridgeConstruction第6頁/共31頁3.AnalysisofEffectofFloatBridgeConstructiononFlowConditionItemstobeanalyzedBackwatercalculationChangeofaverageflowvelocity

SiltcarryingCapacityRiverbedlongitudinaldeformation第7頁/共31頁8第8頁/共31頁93.AnalysisofEffectofFloatBridgeConstructiononFlowConditionFlowQ（m3/s）RiverWidthB（m）AverageWaterDepthH（m）AverageFlowVelocitybeforeBridgeBuildingV（m/sBackwaterHeightduetobearingboat(m)Waterrisingbeforethebearingboat(m)BackwaterExtent(m)Backwaterheightnearthebridgecalculatedobserved5008800.880.650.0180.1602230.0980.0510008801.330.850.0180.2042300.120.0920008802.021.120.0190.2712420.1550.1940008803.071.480.0200.3722520.206Backwatercalculationresult第9頁/共31頁10FlowVelocityChangeDuetoeffectofbackwaternearthebridge,atthesameflowthewaterdepthincreasesandtheaveragesectionflowvelocitydecreases.3.AnalysisofEffectofFloatBridgeConstructiononFlowConditionFlowQ(m3/s)RiverWidthB(m)AverageWaterDepthbeforeBridgeBuilding(m)AverageFlowVelocitybeforeBridgeBuilding(m/s)AverageWaterDepthafterBridgeBuilding(m)AverageFlowVelocityafterBridgeBuilding(m/s)FlowVelocityDecrease(%)5008800.880.650.9780.5810.610008801.330.851.4500.787.820008802.021.122.1751.046.740008803.071.483.2761.396.3flowvelocityslowsdownbyabout6.1%~10.6%.第10頁/共31頁11SiltcarryingCapacityFlowQ(m3/s)AverageFlowVelocitybeforeBridgeBuilding(m/s)AverageFlowVelocityafterBridgeBuilding(m/s)FlowVelocityDecrease(%)SiltCarryingCapacityDecrease(S1-S2)/S1)(%)5000.650.5810.633.310000.850.787.825.420001.121.046.722.140001.481.396.320.73.AnalysisofEffectofFloatBridgeConstructiononFlowConditionSiltcarryingcapacityoftheflowcanbeexpressedas:

SiltunitdischargeCoefficient,3.6FlowvelocityAtsmallflow,thesiltcarryingcapacitydecreasedbyone-third,whichwillgreatlyaffectthesedimentdischargerateoftheflow,forsmallflowprocessoccupiesmosttimesinthelowerYellowRiver.第11頁/共31頁12Lane'sBalanceEquationisusedtoanalyzethebeddeformationthatfloatbridgebuildingmaycause.Lane'sBalanceEquationcanbeexpressedas:ChangeofBedLongitudinalDeformation3.AnalysisofEffectofFloatBridgeConstructiononFlowConditionValuesofBedDeformationafterBridgeConstructionFlowQ(m3/s)Siltcarryingcapacitychange(s1/s2)Averagewaterdepthbeforebridgebuildingh1(m)Waterdepthinbalancedstateafterbridgebuildingh2(m)Averagegradientbeforebridgebuildingi1Gradientinbalancedstateafterbridgebuildingi25001.500.880.9850.000160.0001110001.341.331.4430.000160.0001320001.282.022.1650.000160.0001340001.263.073.2750.000160.00013第12頁/共31頁134.AnalysisofPossibleEffectofFloatBridgeonRiverRegimeChangesEffectofFloatBridgeSectionFixingonRiverRegimeChangesAnalysisofEffectonWorksandFloodplainSafety第13頁/共31頁144.AnalysisofPossibleEffectofFloatBridgeonRiverRegimeChangesInthewanderingreachesofthelowerreachesoftheyellowriver,the"slightbend"schemeisadopted.Nowtheriverregimeofthereachdiffersmuchfromtheplannedrouteandwiththeimprovementoftherivertrainingworks,theriverregimewillberestrainedtotheplannedflowroute.第14頁/共31頁15EffectofFloatBridgeSectionFixingonRiverRegimeChangesForthesafetyoftheFeng-KaiFloatBridge,thebanksatbothendsofthebridgewerereinforced.Thereinforcedendsaresimilartoheadsofoppositegroins,whichwillrestrainthelateralbeddeformationinsmallflowcondition.riverregimeevolutionundertherivertrainingworkswillbebroken.4.AnalysisofPossibleEffectofFloatBridgeonRiverRegimeChanges第15頁/共31頁16EffectonfloodplainsafetyBecauseofbackwaterBackwaterheightcausedbythebridgeisaround2.0cm,andthebackwaterscopeisrelativelyshort,about220m~250m.Therefore,thebridgewillnotcausegreatadverseeffectontheupstreamfloodplainonbothbankswithbackwater.4.AnalysisofPossibleEffectofFloatBridgeonRiverRegimeChanges第16頁/共31頁17OnthepointviewoffixednodesThereinforcedbanksatbothendsofthebridgearelikeheadsofoppositegroin,ontheonehand,theexistingflowroutetendstocausethemainflowtobreakawayfromthecontrolofrivertrainingworksontheotherhand,duetowatercheckofthebridge,theflowlossessomeofitsenergy,sothatthemainflowdoesnothavesufficientpowertoruntothedownstreamworks;moreover,themainflowisscattered,thuseasytoformabnormalriverregimedownstreamofthebridge.Duetothebadeffectofthissituation,whethertheflowislargeorsmall,themainflowmayrushdirectlytothefloodplaindownstreamofthefloatbridge,endangeringtheproductionandlifeinthefloodplain4.AnalysisofPossibleEffectofFloatBridgeonRiverRegimeChanges第17頁/共31頁18ConclusionsUndertheconditionofsmallflow,thebackwatercausedbyfloatbridgebuildingdoesnotextendsfar,norisitquitehigh,therefore,itwillnotproducelargeeffectonfloodcontrol.Thesiltcarryingcapacityofthechannelupstreamofthefloatbridgewilldecrease,whichwillprobablymaketheupstreamchannelmoregentle,therefore,riverregimeregulationwillslowdown.Thelocationofthefloatbridgeisdirectlyrelatedwiththedegreethatitaffectsriverregimechanges.Thefixednodesatbothendsofthefloatbridgeformedduringsmallflowperiodshouldbeconsistentwiththeplannedregulationline.5.ConclusionsandRecommendations第