简介:Thispaperpresentsalaboratorystudyonbridgepierprotectionwithsurfaceguidepanels(SGP)inclear-waterexperiments.TheSGPisinstalledbypiercingasetoftwoverticalpanelspartiallyintothewater,withsomeinteriorangleandleadingopening,settingatadistanceaheadoftheprotectedpier.ThesuitableinstallationoftheSGPcaneffectivelyadjusttheflowpatterntoreducethedownflowmotionandthehorseshoevortexaheadofthepier.WeconsidersomedominantfactorstosetupSGPforpierprotection,includingtheinteriorangleθ,leadingopeningOw,distancebetweenpanelandpierL,submergeddepthofpanelPd,pierdiameterDandwaterdepthH.Afterevaluationoftheseparametersthroughlaboratorytests,theoptimalsetupconditionsofθ=60o,Ow/D=0.1~0.2,L/D=2~2.5andPd/H=0.7aredetermined.Undertheseconditions,theusageofSGPleadstoabestperformanceondecrementofthemaximumscourdepthatpierupto90%withignorablesideeffectsontheSGPscour.
简介:Basedonthe1stordercnoidalwavetheory,thewavediffractionaroundthepiergroupinshallowwaterisstudiedinthispaper.Theformulasforcalculatingthenonlinearwaveforcesarealsopresentedhere.Inordertoverifythetheoreticalresults,modeltestsareconductedinthewaveflumeinTheStateKeyLaboratoryofCoastalandOffshoreEngineeringlocatedinDalianUniversityofTechnology.TherangeofthewaveparametersintheexperimentsischaracteristicwaveperiodTg/d1/2=8.08-22.86,characteristicwaveheightH/d=0.10.45.Theresultsobtainedfromtheexperimentsagreewiththetheoreticalresultsquitewell.Itisshownthat,inshallowwaterthenonlinearwaveforcesactingonapiergrouparegreaterthanthosecalculatedbylinearwavetheory,thevalueofincrementinwaveforceincreaseswiththeincreasesofthenonlinearityofthewave.Inthewaverangestudiedinthispaper,thenonlinearwaveforcecanreachover4timestheforcecalculatecdbylinearwavetheory.Thus,itissuggestedthat,whenTg/d1/2>8,thewaveforceonthepiersinthepiergroupinshallowwatershouldbecalculatedbyusingthecnoidalwavetheory.
简介:-Generallythetoeofthebankslopeinfrontofthepile-supportedpierhastobedredgedtomeettherequirementsofwaterdepthfortheberthofships,whilethetopoftheslopeinrearofthepiermustbebackfilledandelevatedtomakeconnectionswithlandtransportation.Thenthenaturalstateofequilibriumoftheslopeisdestroyed,andsomedeformationanddisplacementareunavoidablyinducedinthesoilmasswhichwillexertanundesirableinfluenceonthepilefoundationofthepier.Thisisatypicalproblemoftheinteractionbetweentheso-called"passivepile"andsurroundingsoil,andhasbeenscarcelystudiedintheliteratureofgeotechnicalengineering.Inthispaper,fieldobservation,modeltestsandnumericalanalysisconductedbytheauthorstostudytheinteractionbetweenpile-supportedpierandbankslopearebrieflydescribedandsomepreliminaryresultsarepresented.
简介:Mobileoffshoredouble-causewaypiersystem,atypeofseashoreunloadingequipment,consistsoftwogroupsofmultipleconnectedsemi-submersiblemodules.Thisstructurehaswideapplicationbecausemostofthemiddleorminitypeofvesselsandshipscanbemooredtoit.Basedontheanalysisofcomputationalmethodsofmulti-bodymotionresponse,ahydrodynamicmodelissetupandthethree-dimensionalpotentialtheoryinfinitedepthisadoptedtocalculatethethree-dimensionalmotionresponseofthissystem.ThedoubleP-Mspectrumisusedtoanalyzethemotionresponseinirregularwaves.Differentwavedirectionsarespeciallytakenintoconsideration,duetotheirvariouseffectstothemotionresponse.Furthermore,thecalculatedresultiscomparedwiththatoftheexperiment,anditisprovedthatsway,heave,pitchandyawmotionaregreatlyconstrainedbymooringsystem.Thecomparisonalsoindicatesthatthemodelcanforecastthemotionperformanceofthetarget,andthatthecalculatedresultcanalsobeusedasreferenceinconnectorandmooringsystemdesign.
简介:Sincelocalscouratbridgepiersinriversandestuariesisamajorcauseofbridgefailure,estimationofthemaximumlocalscourdepthisofgreatimportancetohydraulicandcoastalengineers.Althoughnumerousstudiesthatfocusonscour-depthpredictionhavebeendoneandpublished,understandingoftheflowandturbulencecharacteristicsofthehorseshoevortexthatdrivesthescourmechanisminadevelopingscourholestillisimmature.Thisstudyaimstoquantifythedetailedturbulentflowfieldinadevelopingclear-waterscourholeatacircularpierusingParticleImageVelocimetry(PIV).Thedistributionsofvelocityfields,turbulenceintensities,andReynoldsshearstressesofthehorseshoevortexthatforminfrontofthepieratdifferentscourstages(t=0,0.5,1,12,24,and48h)arepresentedinthispaper.Duringscourdevelopment,thehorseshoevortexsystemwasfoundtoevolvefromoneinitiallysmallvortextothreevortices.Thestrengthandsizeofthemainvortexarefoundtoincreasewithincreasingscourdepth.TheregionsofboththemaximumturbulenceintensityandReynoldsshearstressarefoundtoformatalocationupstreamofthemainvortex,wherethelargeturbulenteddieshavethehighestpossibilityofoccurrence.Resultsfromthisstudynotonlyprovidenewinsightintothecomplexflow-sedimentinteractionatbridgepiers,butalsoprovidevaluableexperimentaldatabasesforadvancednumericalsimulations.
简介:Two-andthree-dimensionalfiniteelementanalysisprogramsforpile-soilinteractionarecompiled.Duncan-Chang'sModelisused.Theconstructionsequenceofthepierismodeled.Thepile-soilinterfaceelementisused.Theinfluenceofthecombinationtypeofpilesonthedeformationofbankslopeandpilebehaviourisanalyzed.Differentdesignsofapile-supportedpierarecomparedthoroughly.Calculationresultsshowthatthestressesanddisplacementsofthepilearedirectlyrelatedtothedistancefromthebankslopeandthedirectionofinclination.Aninclinedproppilesetintherearplatformwouldremarkablyreducethestressesofpilesandthedisplacementofthepier.
简介:Thepier,placedattheoutletofthepressureflowsection,isaneffectivedesigntodealwiththeproblemsofthemanufactureandoperationofthegatesforadischargetunnelwithhighwaterhead.Itiscrucialtocontrolthewater-wing,inducedbythistypeofthepier.Throughobservingthephenomenaofthewater-wing,thereasonofthewater-winginception,i.e.,theconcaveoftheflowsurface,waspresented,andatypeofthenewpierwithbottomunderlaywasdesigned.Thehydrauliccharacteristicsofthepier,includingthevariationsofthewater-wingfeatures,bothlengthandheight,withthewaterhead,aswellaswiththeconcavedepth,andwiththeheightofthebottomunderlay,andthevariationsoftheconcavedepthwiththeheightofthebottomunderlay,wereinvestigatedbyphysicalmodelexperiments.Theresultsshowthattheapproachofthemodificationoftheconcavethroughthestructureswiththebottomunderlay-typepierisremarkablyeffectiveinthewater-wingcontrol.
简介:Inthisstudy,avariationalapproachtothesettlementanalysisofanaxiallyloadedpierem-beddedinamulti-layeredsoilprofileispresented.Inthismethod,thesoilprofileandtheembeddedpieraredividedintoanumberofsub-layersaccordingtotheactualnumberofsoillayersobservedinthefield.ThedisplacementshapefunctionofeachsoillayerisgivenasaproductofanexponentialequationalongthepierdepthandtheBessel’ssolutionintheradialdirection.Thedisplacementrelationshipamongthelayerscanbederivedthroughthetransformationmatrices.Oneofthemajorfeaturesofthismethodisthatthetotalnumberofpierelementsisthesameasthatofsoilsub-layers.Allthefieldcompontents,suchasthedisplacement,stress,andstraininthesoil,canbecalculatedbyclosed-formsolutionsexceptthattheonlyunknownvari-ableisthevalueβwhichcanbedeterminedbyiterationtechniques.Comparisonsweremadewiththeresultsoffiniteelementanalysisandthefieldobservationinpile-loadedtests.
简介:ThistalkwillsummarizetherecentworkrelatedtoakindofnewnanomaterialsproducedbytheSMAT(surfacemechanicalattritiontreatment).Theconceptofsurfacenanocrystallizationofmaterialswillbepresented.Intermsofthegrainrefinementmechanisminducedbyplasticdeformation,anovelsurfacemechanicalattrition(SMA)techniquewasdevelopedforsynthesizingananostructuredsurfacelayeronmetallicmaterialsinordertoupgradetheoverallpropertiesandperformance.ThegrainrefinementmechanismofthesurfacelayerduringtheSMAtreatmentwillbeanalyzedintermsofthenanostructureobservationsinseveraltypicalmaterials.Veryhighyieldstress(5timesofthebasematerial)onthesurfacelayerofthematerialobtainedbytheSMAThasbeenobserved.Theeffectofsurfacenanostructuresonthemechanicalbehaviorandonthefailuremechanismofmetallicmaterialshowsthepossibilitytodevelopanewstrengthgradientcompositeusingco-rollingandnitriding.Theroleofresidualstressinducedduringthetreatmentwillbeinvestigatedanddiscussed.Thedevelopedmaterialsarealsoporosityfreematerialswhichcanbeusedasreferencematerialforthelocalmechanicalbehaviorinvestigationtechniquesuchasthenanoindentation.Ageneralconceptforobtaininghighstrengthandhighductilitynanostructuredmaterialswillbepresented.Theexceptionalhighstrengthandhighductilitysteelshavedeveloped.Thesimulationofthemechanismsforimprovingductilityofhighstrengthnanostructuredmaterialswillbepresented.Thepotentialapplicationsforthelandtransportationvehicles(car,bus,train)andwindenergyhavebeeninvestigated.Someexamplesofconceptdesignfortheintegrationoftheadvancednanostructuredsteelswillbepresented.
简介:ASchwarzschildmicroscopewithanumericalapertureof0.2andamagnificationof130ina100μmfieldofview(FOV)isdesignedandisworkingat13.5nm.Meanwhile,aCCDisusedasadetectorwithapixelsizeof13μm×13μmandimagingareaof13mm×13mm.Theimagingqualitywithtolerancesofsystemanderrorsofmirrorsareconsidered.Weobtainthatthebeston-axesobjectresolutioncanbeuptoabout200nm,theaveragevalueis230nm,andtheresolutionisabout360nmat80μmFOV.