土石坝外文翻译.docx

土石坝外文翻译.docx

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土石坝外文翻译

SafetyInspectionStrategyforEarthEmbankmentDamsusingFullyDistributedSensing

Abstract

Boththechangesintemperatureandstrainduringtheprocessareusedtorevealseriousseepagesandsettlementsoccurringinsidetheembankmentdam.Amethodforseepageandsettlementmonitoringinearthembankmentdamsusingfullydistributedsensingalongopticalfibresisproposed.Theproposedmonitoringsystemalsoofferstheownerthestrategyoftheinspectionandmaintenanceinearthembankmentdams.Thedatabaseinthecontrolandmaintenancecenterisdescribed.Inthispaper,asanexample,amodelfilledwiththesoilfromYellowRiverisbuiltandbareopticalfibersareembeddedunderdifferentsoillayerneartheseepagepath.Theconfigurationofopticalsensingcableinseriesofembankmentdamsisdeveloped.ThesimulatedseepageflowsundervariousflowratesaremonitoredusingtheopticalfibersandmeasuredbyaDiTeSt–STA202distributedtemperatureandstrainanalyzer.Apartialsettlementwithintheembankmentdammodelisobserved.Thecontinuouslydecreasingtemperaturecurveshowsanabruptdramaticincreasingrate,whichshowsthatthechangeisnotcausedbythetemperatureoftheseepagewaterbutthestrain.Theinformationfromthemonitoringcenterprovidesimportantreferencefortheexpertdecision-makingsystemtoensurethesafetyoftheembankmentdamlongrunning.

Keywords:

Embankmentdam;Safetyinspection;Settlementandseepage,Opticalfibersensing

1.Introduction

Embankmentdamsaredesignedtoremainfunctionaldespitesomeacceptablesteadyseepage.Thebackgroundtaskforthesurveillanceofanembankmentdamistomonitorthechangesintemperatureandpressureinsidetheembankmentdaminducedbythoseanomalousseepageswhichmaythreatenthestructureintegrity.Waterpressure,whichisusuallydetectedwithsomeboreholetubesdistributedalongapossibleseepagepath,isatraditionalquantitybeingmonitoredfortrackingaseepageflow[1],[2].Temperaturecannormallybeeasilymeasuredinthestandpipeusingthermometers.Resistivitymeasurementsarecomparablymorecomplicatedsincetheyrequireacomputer-basedmonitoringsystemandminortechnicalinstallationsonthedam.Inspiteoftheeffectivenessofthoseexistingmethods,noneofthemissuitableforcontinuousmonitoring.Withtherecentadvancesinopticalfibersensingtechnology,seepagemonitoringsystemsmeasuringthetemperatureinsidetheembankmentdamusingdistributedsensingalongopticalfibershavebeendeveloped[3].Apreheatedopticalcablemethodisusedinthedamfilledwithconcretecoretodetectseepageflow.Thesensingcableisembeddedatthedamtoefilledwithearthforthetemperaturemeasurementandotherindependentcablesareinstalledatotherplacesforthestrainmeasurement[4].Anyexcessiveandunexpectedseepagemayleadtothefailureoftheembankmentdam,especiallyinunconsolidatedterrains,suchasearth-filledembankmentdams.However,iftemperatureandstrainvaluesarerecordedseparately,whichisdifficultforanearlywarningofthesettlementintheembankmentdamcausedbyseriousseepageorpiping.Moreover,thetemperaturechangeduetotheseepagemaybecomerelativelystablewhenahigherseepagerateflowfindsafixedpaththroughtheembankmentdam.Nevertheless,indangerouscasessuchasthosemassivequake-inducedlakesinChinain2008,theabilityoftheembankmenttomaintainitselfunderhighstressneedstobeinvestigated,sinceitisthemainreferenceinformationforthecrucialdecisiontoeitherdestroytheembankmentdam,ortosluicebyadiversionfacility,ortoreinforcetheembankmentdamtopreventanunexpecteddam-breakintheweakenparts.Withthedevelopmentofscourholes,soilandsands,stonefoundationofspurdikeswillbetakenawaybytherapidflowandthevorticalflow.Evenworse,spurdikemaycollapse,whichhappensinaveryshorttimeandbringserioushazardtovicinityresidents.Therefore,stabilityproblemsmustbedetectedandrepairedinatimelymanner.Alongrodisusuallyemployedtodetectandapproximatetheextentofscour.Sincescouroccursunderwater,inspectionandcircumstancein-fieldareoftenroughanddangerousduringflooding.Themeasurementresultsarethereforerandomandinaccuratewhichcannotbeconsideredasfoundationdatatojudgeifahiddendisasterarises.Anembankmentdamespeciallyforspurdikeslidemonitoringsystembasedonfiberopticsensingtechnologyhasbeenproposed[5].However,thestabilityandsafetyofembankmentdamsarerelatedtomanyimpactfactors,suchasseepageflowwhichisanotherkindofdisaster.Theentireembankmentshouldberoutinelyandcloselyinspectedforseepages,cracks,slides,andsettlements.Theserecordscanhelpdetermineifaconditionisnew,slowlyChanging，orrapidlychanging.Arapidlychangingconditionorthesuddendevelopmentofalargecrack,slide,ordepressionindicatesaveryseriousproblem.Thispaperpresentsanembankmentdamsafetymanagementsystemincludingmonitoringparttomanagerunningconditionrecordsoftheembankmentdam,informationandmakemaintenancestrategy.

2.MaintenanceStrategy

Asuccessfulsafetyandmaintenancesystemprovidesreliableandmeaningfulembankmentdamperformancedatatotheoperationsandengineeringpersonnelwhoareresponsibleforoperatingandmaintainingtheprojects.Themonitoringandmaintainingstrategyofthesystemisessential.Thereareavarietyoftoolsormethodsthatare

availableforembankmentdamhiddendisasterdetectingandmonitoring.Theselectionofmethodstoimplementforaparticularembankmentdamprojectisindesigningasuccessfulmonitoringsystem.Manygoodreferencesthatcurrentlyexistregardingtheselection,design,andinstallationofdamsafetymonitoringinstrumentationareavailable.Opticalfibersensorsareselectedtobuildamonitoringsystemwithhighleveloftechnology,whichperformsgoodmonitoringactivitiesandmainlyaimsattwovariables,thestrainandthetemperaturecorrespondingtotheinformationofthesettlementandtheseepageofembankmentdams.Thismonitoringsystemexcludessomeplaceswhereseriousdestroyhardlyhappenedorsomefailureisunwarrantedtypicallyfailbecausethesystemisviewedastoocomplexanddifficulttoworkwith.Thesystemisreliableandprovideshighqualitydata.Developedprogramshavefriendlyandclearinterfacewhichcompensateperceivedunreliabilityandtheresultofpoor

operationsandmaintenanceproceduresbyusersthatdonotunderstandthetechnology.Howevertheover-useofhightechnologyalsocanresultinhighinstallationcostsrelativetothebenefitsprovided.Thiscanleadtoadecisionnottoimplementtheneededsystemimprovements.Bydevelopinganeffectivedetectionandmaintenancestrategyinthesecases,manyofbetterbenefitscanbeprovided.Aspeciallydesignedconfigurationtotheimplementationcanalsobeverybeneficialinmanagingtherequiredannualcapitalexpenditures,andalsotoaidintheacclimationofoperationsandengineeringpersonneltothenewtechnology.ThesafetymonitoringandmanagementstrategyarchitectureforembankmentdamsisshowninFigure1.Theembankmentsafetyinspectionanddetectionconsists

twoparts.Oneismanualinspectionofminorinstabilities.Thispartismainlyforshortandisolatedcracks,shallow

slideandminorsettlement.Thejobforthesedammanagersistocollectandevaluatethedammonitoringdatabylaboreffort.TheotherpartisautomaticallymonitoringmodulebasedonDiTeSt-STA202instrument.Thispartisespeciallyforlargercracks,deep-seatedslide,andlargersettlement.Amongmid-sizedandbigembankmentdams,implementinglargeamountsofleadingandsensingcablescanprovidesubstantialbenefitsinthequalityandreliabilityofthemonitoring,notlowerthetotalsystemcostincurrentmarketbutsimplifytheconfigurationofthesystem.Applyingtheappropriatestrategyofmaintenanceforthoseparticularwarnedpositionsorsegmentsofembankmentdamswillformasuccessfulmanagementsystemaccordingtobothpartoneandparttwowarningreports.Toaccomplishthisobjective,properstepsanddetailsmustbefollowedinplanninganddesigningthesystem.ThefollowingparagraphsdiscussthemonitoringmodulebasedonDiTeStinstrumentandthedetailsofconfigurationfortwocasesofthesettlementandtheseepage.

1.HiddenDisastMonitoringSystem

3.1Monitoringsystembasedonfiberopticssensors

Informationacquisitionisthefirststepforamanagementsystem.Thefiberopticssensingcableservesassensorunit,whichisbasedonthemechanismofStimulatedBrillouinScattering（SBS）insinglemodeopticalfibers.BymonitoringtheBrillouingainoftheprobelightinfrequencydomain,onecandetectthetemperatureandthestrainalongopticalfibersaroundthesepositionswhereabnormalseepageandthesettlementoccur.Theopticalfibersensorsareembeddedinembankmentdamsandspurdikes.TheconfigurationoftheopticalfibersensorsisshowninFig.2.TherearesomeleadingcablesbetweendifferentspurdikesandembankmentdamsaswellaslinkingDiTeStanalyzer.Fortheseepage,itcanemergeatanylocationonthedownstreamfaceofembankmentdamsthroughtheseepageline.Iftheseepageforcesarelargeenough,thesoilwillbeerodedfromthefoundationandbedepositedinacone-shapedsurfaceneartheoutlet.Theappearanceofthese"boils"isanevidenceofamuddyseepageflowcarryingsoilparticles.Thisshowstheonsetofpipingandacompletefailureofthedammayoccurwithinhours.Itcanbemanuallyinspected,butitmaybelatetoimplementmaintenanceandensurethesafetyofembankmentdams.Theembankmen