黄河铁谢工程弯道改造刍议

-1-DiscussionabouttransformationofcurveconduitofYellowriverTiexieprojectLiuyouzhan(westernhenanYellowRiverAffairsBureau)Abstract:Tiexieprojectwaspassivelybuiltduetorushtodealwithemergency,itisseparatedtotwoup-downbendinnorthgatedam(number10dam).Untillast70centuries,stuffanddescendprojectswererespectivelybuiltinupanddownthedam.Thoughthebuildingofprojectscann’ttransportdownstreamthe10dam,itwassuitedtotemporalwater-sedimentconditions,theriverwasinaperfectcondition.Afterthe“96.8”flooding,theTiexieproject’sinflowpointascendcontinually,sincetheprojectdidn’tdevelopaintegratesmoothbendandwater-sedimentconditionsarechanging,thedisadvantageriverconditionsthatLucunprojectisnearriverbegantoappear.TosettleTiexieprojecttransporteffectively,theemphasesofprojectbendishowtoimprove入溜conditions,makestuffprojectcomplete,makeprojectaintactsmoothbendanduseriverbeddredgeuptoimproveinflow,streamguidanceandoutflowconditionsofriverbedproject.Keywords:Tiexieproject;bend;fluctuatingriver;riverregulation;Yellowriver1thequestionsputforwardYellowriverTiexieprojectisbetweenBaiheandHuimengcountry,Mengjincounty,24kmdownstreamxiaolangdidam,southbankofYellowriver,itisuptoBaipoprojectanddowntoLucunproject,7.45kmtotallengths.TiexieprojectisininitialsectionsdownstreamYellowriver,itplaysaimportantroleincontrollingfloodandrivercircumstances.Inalongtime,becauseTiexieproject’splaneconditionisnotsmooth,outletflowisunsteady,oftenswingsinabout2kmnearLucunproject,thismaketherivercircumstancesbyLucunprojectisveryunsteadyandonlyitsdownsectionisnearriverafter1996.thelongtimeunsteadyofLucunprojectmustdisturbriverconditionsdownstreamandmaketheresultsofriverimprovementfail.SincecomplexriverboundariesofTiexieproject,riverisrestrictedtobridgeandbeachandcann’tadjustitself.Meanwhile,withtheconstructionofxiaolangdi,qixiayuanreservoir,taiaohighspeedyellowriverroadandsoon,riverregimehavesomenewthingsandproblems.Sospeedingatconstructingriverregulation,rebuildingTiexieproject,buildingsmoothandplanflowguidancebendtomakethemsuitedtonewwater-sedimentboundaryconditonsarekeysofthisriverreachregulationandemergentneedsofdownstreamwanderingriverregulation.2.basicconditionsofriverway2.1characteristicsofriverwayThereachofYellowriverTiexieprojectisreachthatistransitedfrommountainareasrivertofluvialplain.Inmountainareas,waterflowdiffusesandvelocityisslow,sand-cobblebedloadwhicharebroughtfromupperravineriverbedcanbedepositedinriversection,sosand-cobbleriverislandthathasseveralflowbranchesdistributaryisdevelopedupperYellowriverroadbridge,LuoYang.Riverislandisconstitutedofscreeandrudesand,itisinthenorthcenterofriverbedandis1m-5mtallerthanriverbed,itstopissandyroamandbottomisroundgravelandscree.Generally,riverbediscoveredbysand-cobble,graindiameterfrom20to200mm,thewidthofriveris2500m,widthofmainriverchannelis500-700m,slopeofriverbedis0.5‰~0.7‰,thedepthofscreedownLuoYangbridgeisgraduallyincreased,itsriverbedisconsistofrudesand,beachisunsteadyandslopeofriverwayis0.265‰.2.2characteristicofwater-sedimentAccordingtoXiaolangdihydraulicstationdatum,theaverageannualdischargeoftheriver-2-regimeis378.38hundredmillionm3from1956to1995,thesedimentdischargeis11.4hundredmilliontons.Averagedischargeis200hundredmillionm3infloodseasons,is53%oftotaldischarges,meanannualdischargeis1300m3/s.thevirtualchangesofsedimentamountsarehigh,30hundredmilliontonsifthesandaremuchand10hundredmillionifitislittle,averagesedimentconcentrationis33.9kg/m3.therewerehighsedimentconcentrationfloodin1996,themosthighsedimentconcentrationis941kg/m3.UntilsluiceinXiaolangdireservoirOctober,1999,downstreamwater-sedimentchangedobviouslyintheaffluenceofthereservoir.Themainfeaturesare:thefluxisobviouslyslower,thescopeoffluxfluctuationdecreased,dischargeisnearlyequalinfloodandunfloodseasons,runoffamountdecreasedmoreobviousinfloodseasons;sedimentamountsdecreasedobviously,meanannualsedimentconcentrationis1.97kg/m3from1999to2002,sedimentrunoffis10615tenthousandtons.Meansedimentconcentrationis0.292kg/m3in2000,annualsedimentrunoffis442tenthousandtons;meansedimentconcentrationis1.43kg/m3in2001,annualsedimentrunoffis2213tenthousandtons,meansedimentconcentrationis4.18kg/m3,annualsedimentrunoffis7960tenthousandtons.2.3erosionanddepositionofriverbedInnaturalcondition,theerosionanddepositionofTiexieriverregimeishigh.Accordingtomeasurementdata,sectionofTiexiedeposited7000m2from1934to1952and4290m2from1952to1960.AfterSanmenxiaReserviorworked,riverregimeerodedobviously.Tiexiesection’swaterleveldecreasedobviouslyfrom1960to1965,itdecreased3.36mwhenthefluxis3000m3/s.Tiexieriversectioncontinuedtoerodeafter1965andreachthebiggestvalue20000m2in1968.SanmenxiaReserviordischargedsedimenttoopenbottomholesin1970,Tiexieriversectionquicklydepositedandreachitsbiggest5000m2in1973.SanmenxiaReserviorsluicedanddischargedsedimentin1974,Tiexiesectionbegantoerode,theaccumulatederosionexceeded10000m2from1976.later,from1977to1999,withthechangesofwater-sediment,Tiexiesectionerodedanddepositedregulations,buttheextentislittle,Tiexiesectioniserodedabout9000m2contrastedtobefore