給排水工程屋頂排水中英文對(duì)照外文翻譯文獻(xiàn)

中英文對(duì)照外文翻譯(文檔含英文原文和中文翻譯)ShortandLongTermAdvantageroofdrainagedesignperformanceDecadehaswitnessedgreatchangesinthedesignoftheroofdrainagesystemrecently,particularly,siphonrainwaterdrainagesystemhasbeengraduallyimproved,andthereislikelytobethekeyapplication.Atthesametimethesechanges,urbandrainagesystemdesignhasundergonetremendouschanges,becausethescopeofawiderurbandrainagesystemdesignforsustainabledevelopment,aswellaspeopleforclimatechangefloodingmoreattention.Themaincontentsofthisarticleishowtodesignroofdrainagesystemsandmakeagoodperformance.Specialattentionishowtogetridofbadhabitsalreadyformedthedesign,butalsoneedtoconsiderinnovativeroofdrainagesystem,suchasgreenroofsandrainwaterharvestingsystems.Practicalapplication:Inthepastfewyears,thedesignoftheroofrainwaterdrainagesystemhasundergonetremendouschanges.Onlargebuildings,siphonrainwaterdrainagetechnologyhasbeenverycommon,aswellasgreenroofsbecauseitisconducivetogreendevelopment,beingmoreandmoreapplications.Takingintoaccounttheongoingresearch,thisarticlefocusesonhowtoeffectivelydesignavarietyofroofrainwaterdrainagesystem,andmakeitachievethedesireddesigneffect.1.IntroductionInthepastdecade,thecityandthewaterdrainagesystemdesignhasbeenwidelyacceptedthinkingaboutsustainableurbandrainagesystem,ortheoptimalmanagementdirection.Themainprinciplesofthedesignofthesesystemsisbothalocallevelinlinewiththequalityofdevelopment,butalsotocreatesomeeconomicbenefitsfortheinvestors.Thisprinciplehasledtothedevelopmentofnewchangesinthesump.Althoughtheapplicationofsuchadeviceisgraduallyreduced,buttheurbanenvironmentrelativelyhighdemandareasstillrequire100%waterproofandrapiddrainage,suchastheroof.Typicallyroofdrainagesysteminthedesign,constructionandmaintenancehasnotbeengivendueattention.Althoughthedrainagesysteminvestmentcostsaccountforonlyasmallportionofthetotalconstructioninvestment,butnotabletojudgethelosscausedbypoordesign.Therearetwodifferentformsofroofdrainagesystemdesignmethods,namelythetraditionalandsiphonmethod.Traditionalsystemsrelyonatmosphericpressurework,thedriveramaffectedsinkflowdepth.Therefore,theconventionalroofdrainagesystemsrequirearelativelylargediameterverticaldroptube,priortodischarge,alldevicesmustbeconnectedtothegroundwatercollectionpipenetwork.Incontrast,siphonicroofdrainagepipesystemsaregenerallydesignedtofullflow(turbulentflowmeansthatrequirelessexhaustpipe),whichwillformanegativepressure,thelargerthehigherflowrateandpressurehead.Typicallysiphonsystemrequireslessdownpipeworkundernegativepressuretothewaterdistributionnetworkcanmeanhigheraltitudework,therebyreducingtheamountofundergroundpipenetwork.Bothsystemsconsistsofthreeparts:theroof,rainwatercollectionpipes,pipenetwork.Alloftheseelementsareabletochangethewaterpressuredistributionsystem.Thissectionfocusesontheroleandperformanceofeachpart.Duetotheprincipleofsiphonsystemhasnotbeenwellunderstood,resultingargumentisrelativelysmall,thisarticlewillhighlightsiphonsystem.2.RoofTheroofisusuallydesignedbythearchitect,designerandnotbythedrainagedesign.Therearethreemainroof.2.1FlatroofFlatroofsareusedinindustrialbuildingslessrainfallregionsandcountries.Thisroofisnotcompletelyflat,butlowerthantheminimumroofslopemayrequire.Forexample,theUnitedKingdomrequiremaximumslopeof10°.Settingminimumslopeinordertoavoidanyunnecessarywater.Despitetheflatroofifitisnotproperlymaintainedwillhavemoreproblems,butitwillreducethedeadzonewithinthebuilding,andtheratioofslopingroofsinfavorofindoorair.2.2slopingroofsMostresidentialandcommercialbuildingsarepitchedroof,inclinedroofisthebiggestadvantagecanquicklydrain,therebyreducingleakage.Intemperateregions,weneedtoconsidercarryingroofsnowload.Onceitrains,rainfallthroughtheslopingroofscanbedeterminedbycalculation.Whenrainfalldatacanbeused,youcanusethekinematictheorytosolvesuchproblems.2.3greenroof(flatorinclined)Itcanproveroofistheoldestgreenroofs,includingrainfallcanreduceordisperseroofplantedwithplants.Itcanbeplantedwithtreesandshrubsroofgarden,itcanalsobeavegetatedrooflightcarpet.Whereinthelattertechniquehasbeenwidelyused.Someoftheseapplicationstendtofocusonaestheticrequirementsandareoftenusedingreendevelopment.Sincetheaestheticrequirementsandpressurerequirements,aswellasgreenroofsthermalinsulationfunction,reducetheheatislandeffect,silencereffect,extendthelifeoftheroof.GreenroofsinGermany,themostwidelyused,followedinNorthAmerica,buttoconsidertheimpactontheaesthetics.Germanyisbyfarthemostexperiencedcountriesinthe19thcenturyhavepracticalapplication,thenasanalternativetoreducetheriskoffiretarroofanoptioninurbanareas.Germanyiscurrentlythemainresearchquestiononthecultivationofotherissuestoconsidersmallercities.Astudyfrom1987to1989,wasfoundpackedwith70mmthickgreenroofcanbereducedby60%-80%ofheatloss.InaCanadianworkcomputermodelbasedontheroofindicatesthataslongasthesump,theareacanreach70%oftheroofareacanbereducedby60percentinoneyear,thesamemodelwasalsousedforartificialrainfall,whichtheresultsindicatethatrainfallinthecatchmentseasonhelpstodrainawayrainwater.However,noneofthesestudiesshowthatgreenroofscanplayausefulroleintherainfallseason,orhowhighcollectionefficiencyofwatersupply.TheUnitedStatesdidsometests,aslongasthegreenroofsregularwatering,canreduce65percentoftherunoffinarainfall.America'smostauthoritativegreenroofguidelinesbytheNewJerseystateenvironmentalagenciespromulgated.Themainprincipleistosolvethestructuralproblemsoflight,andhowcanthenormaldrainageaftertwoyears.Rainfallperiodisbasedontheprobabilityoffailureisdetermined.Thesystemistypicallybasedonrainfallduringrainstormstwominutes,twominutes,haveachoice.Althoughthismodelwillgetmoretraffic,butthereisnootherbetteralternative.Studieshaveshownthatthetraditionalmodelisappliedtostudygreenroofsarepremature.Lossfactorthantraditionalroofrecordsshouldbesmall,about98.7%.Peakflowwillbereduced,althoughnotpenetrate,thesurfaceroughnessbutalsohaveasignificantimpact.Concentratedrainfallthantwominutesforalongtime,especiallyforlargeroofareas,suchaspublicbuildings,commercialbuildings,industrialbuildings.Urbandrainagedesignshouldalsoconsiderotherfactors,foracomplexsystem,agreenroofinarainisnotenough.Waterflowdurationcurveshowsalongerthantraditionalsystems.Andtwoindependentandwillaffectbetweenispossible,whichrequiresamoreprecisetimeperiod.3.RainwaterCollectorBasicrequirementsrainwatercollectorisdesignedtobeabletoaccommodaterainfallrainstorms.Althoughitispossibletomakeaslightlyinclinedroofdrainagepurposes,butthenatureoftheconstructionindustryandbuildingsettlementwillbecomeflatroofTypically,thetankisplacedinahorizontal,sectionalviewofthewaterisoutwardlyinclined,whichtheroleofhydrostatic.3.1drainoutletAnalyzingrainwatercollectorhassufficientvolumeisthekeytothesumpoutletexternalsettingconditions.Alsoaffecttheflowrateintothestormwaterdrainagesystempiping,butalsoaffectthedepthofthewatercatchment.Althoughthedepthofthesumpwillnotbringanyparticularproblems,buttoodeepcancauseexcessivesump.Numerousstudiesinthe1980sshowedthattheflowofconventionalroofdrainagesystemoutletcanbedividedintotwocases.Itdependsonthesizeofthedepthandsizeoftheoutlet.Whenthewaterdepthislessthanhalfthediameteroftheoutlet,theflowofthefirsttype,andtheoutletoftheflowcanbecalculatedbyanappropriateequation;waterdepthincreases,exportsareslowlycloggingtheflowwillbecomeanotherformforms,atthesametime,theflowofexportscanbeobtainedthroughotherequations.Whileconventionalroofdrainagesystemsaredesignedtobefree-draining,butmaycauselimitationsencounteredinthedesignoftheflowisnotfree.Inthiscase,itwillrequireadditionaldepth.Siphonroofdrainagesystems,theoutletisdesignedtobesubmergedstream.Inthiscase,thedepthoftheoutletofthedecisionismorecomplicated,becausethedesignofthesumpdependsontheflow.Recentstudieshaveshownthatconventionalroofdrainagesystemsuseavarietyofnon-standardcatchment,theirdepthandheight,biggerthanthediameteroftheoutlet.Thiswilleventuallyresultinasiphoneffect.Foragivencatchment,theflowdependsonthestartingendofthedroptubediameter.Asimilarphenomenonhasalsobeenusedtostudythestandardcatchment,inthesecircumstances,onlylimitedsiphonactionoccurswithinrelativelyclosedistancefromtheexit.3.2tankflowclassificationInthecomplexflowsumpoutletflowclassification,canbeseenfromTable2a,theflowwillbeuniformlayering,regardlessofwhetherthesameinletflow.Table2band2cshow,exportdistributionwillgreatlyinfluencetheflow.Whentheoutletisnotafreejet,sumpoutletcomplexflowclassificationisdifficulttodescribe.Becauseeachcatchmenttankpressuresarelikelytobemerged.Forexample,thesiphontubesystemdesignpointisatnearfulljetoutletflowclassificationdependsontheenergylossofeachbranch.3.3hydrostaticsectionalSumpshapeofthewatersurfaceinthecanalcanbeclassifiedaccordingtotheflowequation.Inmostcases,alowflowratemeansthatthereislessfrictionloss,ifexportsarefreejet,thefrictionlossisnegligiblecross-sectionthroughthehydrostaticequation1todeterminethehorizontaldistance.WhereQ--flow(m3/s)T-surfacewidth(m)g-accelerationofgravity(m/s2)F-flowarea(m2)Equation1cannotbeignoredwhenthefrictionrequiredtocorrect(orverylongpipevelocityislarge),ornotafreejet.3.4ThecurrentdesignmethodsThepreviousdiscussionhashighlightedthemainfactorsthatshouldbeconsideredwithsinkdesign.However,withoutthehelpofacertainnumberofmodels,computinghydrostaticsectionalroofdrainagesystem,thevolumeofthesumpispossible.Thislargecommercialandmanufacturingindustry,isadevelopmentopportunity,youcanmergeseveralkilometersofwaterroutes.Thus,theconventionaldrainagesystemsumpdesignmethodsaremainlybasedonexperience,andassumethatexportsarefreejet.Sumplocationinthebuilding,itmaycausetheexampletofail.DifferentinterfacesumpExceptinthecasecitedabove,butalsoallowsdesignerstouseempiricaldata.3.5DigitalModelLargenumberofdigitalmodelscanbeusedtoaccuratelydescribetheflowofanyformofcatchmenttank,regardlessofwhethertheroofflowsstable.Anexampleofthismodelisacombinationofroofspacemodel.Thismodelenablesuserstoclassifydifferentaspectsofthedataindicated,includes:detailsoftherains,theroofsurfacedrainageandotherdetails.Kinematicshavealsobeenusedtostudyrainwatertanktoflowfromtheresearchcollection.Atypicalmethodisbasedonopensystemtosolveabasicproblemofspatialmobility.Thismodelautomaticallyresolvethesumpoutletflowsituation,butalsotodealwiththecaseoffreejetcanalsobesimulatedspacelimitedmobilityandsubmergeddischarge.Outputvalues??includedepthandflowrate.Currently,themodelisessentiallyjustavarietyofresearchtools,butalsothroughpracticalengineeringtest.However,weshouldfaceuptothevariousrolemodels.4pipesystemsgroupCompositionintheformandscopeofthetubegroupdeterminestheroofdrainagesystemreliesmainlyonthetraditionalsystemorsiphonaction.4.1TraditionalstormwatersystemsConventionalroofdrainagesystems,thegroundplaneisgenerallyverticalpipe-linenetwork,connectedtothesumpoutletandundergrounddrainagesystems,criticalsystemsaswellascompensatingtube.Itshouldbeemphasizedthattheanglebetweenthegroundandthecompensatingtubeislessthan10°.Capacityoftheentiresystemreliesmainlyontheoutlettubeinsteadofdown.Flowverticaltubeisusuallyfree-flowing,fullofonly33%,theefficiencydependsontheexcesslengthofthetube.Ifthedroptubelongenough(typicallygreaterthan5m),theremaybeanannularflow.Similarly,undernormalcircumstancesflowcompensationpipeisfree-flowing,fullofupto70%.Suchdesignedprocessbothforthedesign,variousequationscanalsobeused.4.2SiphonroofdrainagesystemIncontrastwiththetraditionaldrainagesystems,Siphonroofdrainagesystemreliesonairflowoutsidethesystem,andthetubeisfullpipeflowstream.Thedesignsareusuallymadeontheassumptionthatthedesignofheavyrain,thesystemcanquicklysiphondischargerainwater.Thisassumptionallowstheapplicationofhydrostaticsiphonsystemtheory.Oftenusedsteadyflowenergyequation.Whilethisapproachignoresthesmallamountofenergylossattheentrance,butaftertheexperimentshowedthattherearestillconducivetopracticaluse.However,steady-statedesignmethodsinthesiphonsystemisexposedtorainwhenthesystemdoesnotmeetthestandardrequirementsorchangesinrainfallintensityislargeisnotapplied.Inthefirstcase,therewillbesomemixingofairquality,annularflowoccurs.Theseproblemsarenotintegratedinthesystemwhenmoreserious.Becauseusuallydesignedrainsarecommon,itisclearnowdesignmethodologyovertimemaynotapplytosiphonsystem.Thisisamajordisadvantage,becausethedesignofthemainproblemisthenoiseandvibrationproblems.Despitethedisadvantagesofthepriordesignapproach,butalotoftheworld'sveryfewengineeringfailurereports.Whenafailureoccurs,mostlikelyforthefollowingreasons:AnincorrectunderstandingoftheoperationpointsSubstandardmaterialslistInstallationdefectsMaintenancemismanagementToovercomethesedisadvantages,wehaverecentlylaunchedaseriesofresearchprojects,todiscussthesiphonsystem,andthedevelopmentofdigitalmodels.Fromthisworkwelearnalot.Incontrastwithconventionaldesignmethodsofsomeassumptions,siphonsystemmainlyhasthefollowingaspects:1)non-flowsystemoffullflow2)levelsofcertainpipe-flowingfullpipeflow3)fullpipeflowdownstreampropagationthroughaverticalpipe,riser,etc.4)theinnertubeflowoccursovertheverticalsection,thesystemtoreducethepressure5)downwardtubeisfullpipeflow,therewillbeairlock6)appearscompletelysiphonactionuntilwellintotheairsystemislowerthanacertainlevelTable4acolumndataindicatethatbelowthedesignpoint,thesystemwillsiphonunstableflow,depthofthewatercollectingtankisinsufficienttomaintainthesiphonaction.Table4bshowthattheunsteadyflowinsiphonsystemwhenitwillappear.Table5liststhedataoutputofadigitalmodel.Itcanbeseenthatthemodelcanaccuratelydescribethesiphonaction,siphonandsteadystate,thedataalsoshowthatthemodelcanaccuratelydescribethecomplexsiphonaction.5ConclusionThisarticlehasillustratedthecriticalroofdrainagesystems,buttheseareoftenoverlookedintheurbandrainagesystemdesign.Thisarticlealsoshowsthatthedesignprocessisacomplexprocess,relymainlyontheperformanceofexports.Thefollowingconclusionsarebasedonthedesignsummedup:1)Rundependonthreeinteractingparts:theroof,sump,waterpipes2)Greenroofscanreducetrafficandbeautifythecity3)theexportperformanceofthesystemisessential4)siphondrainagesystemhaveagreateradvantageinlarge-scaleprojects,butmustbeconsideredhighmaintenancecosts5)DesignsiphondrainagesystemshouldconsideradditionalcapacityandoperationalissuesAlthoughthegreenroofisamoreattractiveoption,butthetraditionalroofofabuildinginthecountrywillcontinuetodominate.Greenroofswillbegraduallydeveloped,andgraduallybeenwidelyaccepted.Similarly,theroofdrainagesystemshowneffectivethatitwillcontinuetoplayahugeroleinthecommercialbuildingdrainagesystems.Roofdrainagesystemofthegreatestthreatsfromclimatechange,existingsystemstendtobenotsimplyaging;rainfallpatternsofchangewillresultininefficientoperation,self-cleaningratewillbereduced.Changesinwindspeedandtheroofwillalsoacceleratetheagingoftheroof,itisnecessarytocarryoutmaintenance.Takingintoaccounttheclimatechange,theincreaseinmaterials,roofcollectedrainwaterwillbemoreextensive.Currently,theamountofrainaroundtheglobeperpersonperday7-300litersintheUK,withanaverageconsumptionof145L/h/d,ofwhichonlyaboutoneliterisusedbypeople,about30percentofthetoilet,studyshowsIfwatershortage,rainwatercollectedontheroofofdevelopedanddevelopingcountriesarerecommendedapproach.屋頂排水設(shè)計(jì)性能的近期與遠(yuǎn)期優(yōu)勢(shì)最近十年見證了屋頂排水系統(tǒng)設(shè)計(jì)方面的巨大變化，特別的是，虹吸雨水排水系統(tǒng)已經(jīng)得到逐步改善，并且有可能得到重點(diǎn)應(yīng)用。發(fā)生這些變化的同時(shí)，城市排水系統(tǒng)設(shè)計(jì)已經(jīng)發(fā)生了巨大的變化，因?yàn)檫m用范圍更廣的可持續(xù)發(fā)展城市排水系統(tǒng)設(shè)計(jì)，還有人們對(duì)于氣候變化帶來的洪水泛濫的更多關(guān)注。這篇文章的主要內(nèi)容就是，如何設(shè)計(jì)屋頂雨水排水系統(tǒng)并使之有良好的運(yùn)行性能。需要特別注意的是如何改掉已經(jīng)形成的不良設(shè)計(jì)習(xí)慣，同時(shí)還要需要考慮屋頂排水系統(tǒng)的創(chuàng)新，如綠色屋頂和雨水收集系統(tǒng)。實(shí)際應(yīng)用：在過去幾年，屋頂雨水排水系統(tǒng)的設(shè)計(jì)已經(jīng)發(fā)生了巨大的變化。在大型建筑物上，虹吸雨水排水技術(shù)已經(jīng)很常見，還有綠色屋頂由于其有利于綠色發(fā)展，正得到越來越多的應(yīng)用?？紤]到正在進(jìn)行的研究，本文主要介紹如何有效地設(shè)計(jì)各種不同的屋頂雨水排水系統(tǒng)，并使其達(dá)到理想的設(shè)計(jì)效果。1.緒論在過去十年，城市與水排水系統(tǒng)設(shè)計(jì)已經(jīng)想著廣為接受的可持續(xù)發(fā)展城市排水系統(tǒng)或者最優(yōu)管理方向發(fā)展。設(shè)計(jì)這些系統(tǒng)主要原則是，既要有符合當(dāng)?shù)匕l(fā)展水平的質(zhì)量，又要為投資者創(chuàng)造一定的經(jīng)濟(jì)效益。這種原則已經(jīng)引發(fā)了集水池發(fā)展方式新的變化。盡管這種裝置的應(yīng)用正在逐漸減少，但是城市環(huán)境要求比較高的地區(qū)仍然要求100%防水且排水迅速，例如屋頂。通常屋頂排水系統(tǒng)在設(shè)計(jì)、建造和維護(hù)時(shí)并沒有受到應(yīng)有的重視。盡管排水系統(tǒng)的投資費(fèi)用只占建筑總投資的一小部分，但是，并不能據(jù)此來判斷設(shè)計(jì)不良帶來的損失。主要有兩種不同形式的屋頂排水系統(tǒng)設(shè)計(jì)方法，分別是傳統(tǒng)的和虹吸式方法。傳統(tǒng)的系統(tǒng)依靠大氣壓力工作，其驅(qū)動(dòng)壓頭受到水槽流動(dòng)深度的影響。因此傳統(tǒng)的屋頂排水系統(tǒng)需要一個(gè)直徑相當(dāng)大的垂直下降管，在排放之前，所有的裝置都必須連接到地下水收集管網(wǎng)。與此相反，虹吸式屋頂排水系統(tǒng)通常設(shè)計(jì)成滿管流（紊流狀態(tài)意味著只需要較小的排氣管），從而會(huì)形成負(fù)壓，較大的壓頭和較大的流速。通常虹吸式系統(tǒng)需要較少的下降管，在負(fù)壓狀態(tài)下工作，意味著給水管網(wǎng)可以較高的高度上工作，從而減少地下管網(wǎng)量。兩種系統(tǒng)都由三部分組成：屋頂，雨水收集管道，系統(tǒng)管網(wǎng)。所有這些部分都能夠改變系統(tǒng)的水壓分布。這部分主要關(guān)注各部分的作用和性能。由于虹吸系統(tǒng)的工作原理并沒有得到很好的理解，得到的論證比較少，本文將會(huì)重點(diǎn)介紹虹吸系統(tǒng)。2.屋頂通常屋頂是由建筑師設(shè)計(jì)的，而不是由排水設(shè)計(jì)者設(shè)計(jì)的。主要有三種屋頂。2.1平屋頂平屋頂主要應(yīng)用在降雨量比較少的地區(qū)和發(fā)達(dá)國家的工業(yè)建筑。這種屋頂并不完全是平的，而是低于所規(guī)定的屋頂最小坡度。例如，英國規(guī)定最大坡度為10°。設(shè)定最小坡度是為了避免任何不必要的積水。盡管平屋頂如果得不到正確的維護(hù)會(huì)產(chǎn)生較多的問題，但它會(huì)減少建筑物內(nèi)的死區(qū)，且比斜屋頂有利于室內(nèi)氣流組織。2.2斜屋頂大多數(shù)居住建筑和商業(yè)建筑都是斜屋頂，斜屋頂最大的優(yōu)點(diǎn)是可以迅速排水，從而可以減少漏水。在溫帶地區(qū)，不需要考慮屋頂承載的降雪載重。一旦下雨，斜屋頂通過的降雨量就可以通過計(jì)算確定。當(dāng)有降雨資料可以利用時(shí)，可以使用運(yùn)動(dòng)學(xué)理論來解決這類問題。2.3綠色屋頂（平的或者是斜的）可以證明最老的屋頂就是綠色屋頂，它包括可以減少或驅(qū)散降雨的種有植物的屋頂。它可以是種有樹和灌木的屋頂花園，也可以是長有植被的輕型屋頂?shù)靥?。其中后一種技術(shù)已經(jīng)得到廣泛應(yīng)用。其中一些應(yīng)用趨向于側(cè)重美學(xué)要求并經(jīng)常應(yīng)用于綠色發(fā)展。由于審美要求和水壓要求，綠色屋頂還有熱絕緣的功能，減少熱島效應(yīng)，有消聲作用，延長屋頂?shù)氖褂脡勖?。綠色屋頂在德國應(yīng)用最為廣泛，在北美地區(qū)次之，但是要考慮美學(xué)上的影響。德國是目前為止最有經(jīng)驗(yàn)的國家，早在19世紀(jì)就有實(shí)際應(yīng)用，當(dāng)時(shí)作為在城市地區(qū)替代焦油屋頂降低火災(zāi)危險(xiǎn)的一種選擇。目前德國主要研究放在種植問題上，對(duì)城市的其它問題考慮較少。從1987年到1989年的一項(xiàng)研究工作，發(fā)現(xiàn)裝有70毫米厚的綠色屋頂可以減少60%-80%的熱損失。在加拿大的一項(xiàng)基于電腦模型的工作，表明在屋頂只要集水器是、的面積能夠達(dá)到屋頂面積的70%，在一年內(nèi)就能減少60%，同樣的模型也被用于人工降雨，其結(jié)果都表明集水器在降雨季有助于雨水排走。但是這些研究都沒有表明綠色屋頂在降雨季可以發(fā)揮多大的作用，或者給水管的收集效率有多高。美國做了一些測(cè)驗(yàn)，只要對(duì)綠色屋頂經(jīng)常的澆灌，就可以在一次降雨中減少65%的徑流量。美國最有權(quán)威的綠色屋頂指導(dǎo)原則是由新澤西州環(huán)保部門頒布的。這項(xiàng)原則主要是解決輕型結(jié)構(gòu)問題，以及如何在兩年之后還能正常的排水。降雨周期是根據(jù)是根據(jù)失敗的概率決定的。通常的系統(tǒng)是根據(jù)暴雨期間兩分鐘的降雨量，這兩分鐘是有選擇的。盡管這種模型會(huì)得到更高的流量，但是沒有其他更好的替代方法。研究表明，傳統(tǒng)模型應(yīng)用于綠色屋頂?shù)难芯渴鞘遣怀墒斓摹Ａ魇Я肯禂?shù)比傳統(tǒng)屋頂記錄的要小，大約為98.7%.峰值流量也會(huì)減少，雖然沒有滲透，但是表面粗糙度也會(huì)產(chǎn)生顯著的影響。集中降雨的時(shí)間要比兩分鐘要長，特別是對(duì)面積較大的屋頂，如公共建筑、商業(yè)建筑、工業(yè)建筑。城市排水設(shè)計(jì)還要考慮其他一些因素，對(duì)于一個(gè)復(fù)雜的系統(tǒng)來說，一個(gè)綠色屋頂在一場降雨中是不夠的。流量水位曲線顯示的持續(xù)期要比傳統(tǒng)系統(tǒng)長。并且兩場獨(dú)立的將與之間的影響也是有可能的，這需要更加精確的時(shí)間周期。3.雨水收集器雨水收集器的基本要求是要能夠容納設(shè)計(jì)暴雨時(shí)的降雨量。盡管通常情況下可以通過讓屋頂稍微傾斜來達(dá)到排水的目的，但是建筑工業(yè)的性質(zhì)及建筑物的沉降都會(huì)式屋頂變得平坦，在水平放置的水槽中，水的剖面是向外傾斜的，這是流體靜力學(xué)的作用。3.1排水溝出口的深度判斷雨水收集器是否具有足夠容積的關(guān)鍵是集水器外部出口的設(shè)置情況。還會(huì)影響流入雨水排水系統(tǒng)管道的流速，還會(huì)影響集水器的積水深度。盡管集水器的深度不會(huì)帶來什么特別的問題，但是過深會(huì)導(dǎo)致集水器過高。20世紀(jì)80年代的大量研究表明，傳統(tǒng)屋頂排水系統(tǒng)的出水口的流動(dòng)情況可以分為兩種情況。這取決于水深與出口尺寸的大小。當(dāng)水深小于出口直徑的一半時(shí)，流動(dòng)情況是第一種類型，并且出口的流動(dòng)情況可以通過合適的方程計(jì)算出；隨著水深的增加，出口會(huì)被慢慢堵塞，流動(dòng)形式會(huì)變成另一種形式，同時(shí)，出口的流動(dòng)情況可以通過其他方程得出。盡管傳統(tǒng)屋頂排水系統(tǒng)被設(shè)計(jì)成可以自由排水，但是設(shè)計(jì)中遇到限制可能會(huì)使出流不是自由的。在這種情況下，就會(huì)需要額外的深度。在虹吸式屋頂排水系統(tǒng)中，出水口被設(shè)計(jì)成淹沒出流，。在這種情況下，決定出水口的深度比較復(fù)雜的，因?yàn)榧鞯脑O(shè)計(jì)取決于流動(dòng)情況。近期的研究表明，傳統(tǒng)的屋頂雨水排水系統(tǒng)使用各種非標(biāo)準(zhǔn)的集水器，它們的深度和高度，都要比出口的直徑大。這最終會(huì)造成虹吸作用。對(duì)于一個(gè)給定的集水器，始端的流動(dòng)情況取決于下降管的直徑。類似的現(xiàn)象也被用于研究標(biāo)準(zhǔn)的集水器，在這些情況下，受限的虹吸作用只發(fā)生在離出口比較近的距離內(nèi)。3.2槽內(nèi)的流動(dòng)分類在集水槽復(fù)雜流動(dòng)出口的流動(dòng)分類中，可以從表2a中看出，流動(dòng)會(huì)出現(xiàn)均勻的分層，而不管入口的流動(dòng)情況是否相同。表2b和2c表明，出口的分布會(huì)極大的影響流動(dòng)情況。當(dāng)出口不是自由射流時(shí)，集水槽中復(fù)雜出口的流動(dòng)情況分類是很