水利水电工程毕业设计英文翻译混凝土重力坝.docx
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水利水电工程毕业设计英文翻译混凝土重力坝.docx
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水利水电工程毕业设计英文翻译混凝土重力坝
ConcreteGravityDam
Thetypeofdamselectedforasitedependsprincipallyontopographic,geologic,hydrologic,andclimaticconditions.Wheremorethanonetypecanbebuilt,alternativeeconomicestimatesarepreparedandselectionisbasedoneconomicaconsiderations.Safetyandperformanceareprimaryrequirements,butconstructiontimeandmaterialsoftenaffecteconomiccomparisons.
DamClassification
Damsareclassifiedaccordingtoconstructionmaterialssuchasconcreteorearth.Concretedamsarefurtherclassifiedasgravity,arch,buttress,oracombinationofthese.Earthfilldamsaregravitydamsbuiltofeitherearthorrockmaterials,withparticularprovisionsforspillwaysandseepagecontrol.
Aconcretegravitydamdependsonitsownweightforstructuralstability.Thedammaybestraightorslightlycurved,withthewaterloadtransmittedthroughthedamtothefoundationmaterial.Ordinarily,gravitydamshaveabasewidthof0.7to0.9theheightofthedam.Solidrockprovidesthebestfoundationcondition.However,manysmallconcretedamsarebuiltonpreviousorsoftfoundationsandperformsatisfactorily.Aconcretegravitydamiswellsuitedforusewithanoverflowspillwaycrest.Becauseofthisadvantage,itisoftencombinedwithanearthfilldaminwidefloodplainsites.
ArchdamsarewellsuitedtonarrowV-orU-shapedcanyons.Canyonwallsmustbeofrocksuitableforcarryingthetransmittedwaterloadtothesidesofthecanyonbyarchaction.Archsectionscarrythegreatestpartoftheload;verticalelementscarrysufficientloadthroughcantileveractiontoproducecantileverdeflectionsequaltoarchdeflections.Ordinarily,thecrestlength-to-heightratioshouldbelessthan5,althoughgreaterratioshavebeenused.Generally,thebasewidthofmodernarchdamsis0.1to0.3theheightoftheimpoundedwater.Aspillwaymaybedesignedintothecrestofanarchdam.
Multiplearchessimilarlytransmitloadstotheabutmentorendsofthearch.Thistypeofdamissuitedtowidervalleys.Themainthrustandradialshearsaretransmittedtomassivebuttressesandthenintothefoundationmaterial.
Buttressdamsincludeflat-slab,multiple-arch,roundhead-buttress,andmultiple-dometypes.Thebuttressdamadaptstoallsitelocations.Downstreamfaceslabsandapronsareusedforoverflowspillwayssimilartogravitydamspillways.Inclinedslidinggatesorlight-weightlow-headgatescontroltheflow.
Thewaterloadsaretransmittedtothefoundationbytwosystemsofload-carryingmembers.Theflatslabs,arches,ordomessupportthedirectwaterload.Thefaceslabsaresupportedbyverticalbuttresses.Inmostflat-slabbuttressdams,steelreinforcementisusedtocarrythetensionforcesdevelopedinthefaceslabsandbuttresssupports.Massive-headbuttresseseliminatemosttensionforcesandsteelisnotnecessary.
Combiantiondesignsmayutilizeoneormoreofthepreviouslymentionedtypesofdams.Forexample,studiesmayindicatethatanearthfilldamwithacenterconcretegravityoverflowspillwaysectionisthemosteconomialinawide,flatvalley.Otherdesignconditionsmaydictateamultiple-archandbuttressdamsectionorabuttressandgravitydamcombination.
SiteExploration
Thedamlocationisdeterminedbytheproject’sfunctions.Theexactsitewithinthegenerallocationmustbedeterminedbycarefulprojectconsiderationandsystematicstudies.
Inpreliminarystudies,twoprimaryfactorsmustbedetermined-thetopographyatthesiteandcharacteristicsofthefoundationmaterials.Thefirstchoiceofthetypeofdamisbasedprimarilyonthesetwofactors.However,thefinalchoicewillusuallybecontrolledbyconstructioncostifothersitefactorsarealsoconsidered.
Asiteexplorationrequiresthepreparationofanaccuratetopographicmapforeachpossiblesiteinthegenerallocation.Thescaleofthemapsshouldbelargeenoughforlayout.Explorationprimarilydeterminestheconditionsthatmakesitesusableorunusable.
Fromthesiteexplorations,tentativesketchescanbemadeofthedamlocationandprojectfeaturessuchaspowerplants.Physicalfeaturesatthesitemustbeascertainedinordertomakeasketchofthedamanddeterminethepositionofmaterialsandworkplantduringconstruction.Otherfactorsthatmayaffectdamselectionareroadways,fishways,locks,andlogpassages.
Topography
Topographyoftendeterminesthetypeofdam.Forexample,anarrowV-shapedchannelmaydictateanarchdam.Thetopographyindicatessurfacecharacteristicsofthevalleyandtherelationofthecontourstothevariousrequirementsofthestructure.Soundnessoftherocksurfacemustbeincludedinthetopographicstudy.
Inalocationstudy,oneshouldselectthebestpositionforthedam.Anaccuratesketchofthedamandhowitfitsintothetopographicfeaturesofthevalleyareoftensufficienttopermitinitialcostestimates.Thetentativelocationoftheotherdamfeaturesshouldbeincludedinthissketchsinceitemssuchasspillwayscaninfluencethetypeandlocationofthedam.
Topographicmapscanbemadefromaerialsurveysandsubsequentcontourplottingortheycanbeobtainedfromgovernmentalagencies.Thetopographicsurveyshouldbecorrelatedwiththesiteexplorationtoensureaccuracy.Topographicmapsgiveonlythesurfaceprofileatthesite.Furthergeologicalandfoundationanalysesarenecessaryforafinaldeterminationofdamfeasibility.
FoundationandGeologicalInvestigation
Foundationandgeologicalconditionsdeterminethefactorsthatsupporttheweightofthedam.Thefoundationmaterialslimitthetypeofdamtoagreatextent,althoughsuchlimitationscanbecompensatedforindesign.
Initialexplorationmayconsistofafewcoreholesdrilledalongthetentativelyselectedsitelocation.Theiranalysisinrelationtothegeneralgeologyoftheareaoftenrulesoutcertainsitesasunfeasible,particularlyasdamheightincreases.Oncethenumberofpossiblesitelocationshasbeennarroweddown,moredetailedgeologicalinvestiagtionsshouldbeconsidered.
Thelocationofallfaults,contacts,zonesofpermeability,fissures,andotherundergroundconditionsmustbeaccuratelydefined.Theprobablerequiredexcavationdepthatallpointsshouldbederivedfromthecoredrillanalysis.Extensivedrillingintorockformationsisn’tnecessaryforsmalldams.However,asdamheightandsafetyrequirementsincrease,investigationsshouldbeincreasedindepthandnumber.Iffoundationmaterialsaresoft,extensiveinvestigationsshoulddeterminetheirdepth,
permeability,andbearingcapacity.Itisnotalwaysnecessaryorpossibletoputaconcretedamonsolidrock.
Thedifferentfoundationscommonlyencounteredfordamconstructionare:
(1)solidrockfoundations,
(2)gravelfoundations,(3)siltorfinesandfoundations,(4)clayfoundations,and(5)nonuniformfoundationmaterials.Smalldamsonsoftfoundation(item2throughitem5)presentsomeadditonaldesignproblemssuchassettlement,preventionofpiping,excessivepercolation,andprotectionoffoundationfromdownstreamtoeerosion.Theseconditionsareabovethenormaldesignforcesofaconcretedamonarockfoundation.Thesameproblemsalsoexistforearthdams.
Geologicalformationscanoftenbepicturedincross-sectionbyaqualifiedgeologistifhehascertaincoredrillholesuponwhichtobasehisoverallconceptofthegeology.However,theplansandspecificationsshouldnotcontainthisoverallgeologicalconcept.Onlythelogsofthecoredrillholesshouldbeincludedforthecontractor’sestimates.However,thegeologicalpictureoftheunderlyingformationsisagreataidinevaluatingthedamsafety.Theappendixconsistsofexcerptsfromageologicreportforthesiteusedinthedesignexamples.
Hydrology
Hydrologystudiesarenecessarytoestimatediversionrequirementsduringconstruction,toestablishfrequencyofuseofemergencyspillwaysinconjunctionwithoutletsorspillways,todeterminepeakdischargeestimatesfordiversiondams,andtoprovidethebasisforpowergeneration.Hydrologicstudiesarecomplex;however,simplifiedproceduresmaybeusedforsmalldamsifcertainconservativeestimatesaremadetoensurestructuralsafety.
Formulasareonlyaguidetopreliminaryplansanddesigncomputations.Theempiricalequationsprovideonlypeakdischargeestimates.However,thedesignerismoreinterestedintherunoffvolumeassociatedwithdischargeandthetimedistributionoftheflow.Withthesedata,thedesignerknowsboththepeakdischargeandthetotalinflowintothereservoirarea.Thisprovidesabasisformakingreliablediversionestimatesforirrigationprojects,watersupply,orpowergeneration.
Areliablestudyofhydrologyenablesthedesignertoselecttheproperspillwaycapacitytoensuresafety.Theimportanceofasafespillwaycannotbeoveremphasized.Insufficientspillwayshavecausedfailuresofdams.Adequatespillwaycapacityisofparamountimportanceforearthfillandrockfilldams.Concretedamsmaybeabletowithstandmoderateovertopping.
Spillwaysreleaseexcesswaterthatcannotberetainedinthestoragespaceofthereservoir.Inthepreliminarysiteexploration,thedesignermustconsiderspillwaysizeandlocation.Siteconditionsgreatlyinfluencetheselectionoflocation,type,andcomponentsofaspillway.Thedesignflowsthatthespillwaymustcarrywithoutendangeringthedamareequallyimportant.Therefore,studyofstreamflowisjustascriticalasthefoundationandgeologicalstudiesofthesite.
附录2外文翻译
混凝土重力坝
一个坝址的坝型选择,主要取决于地形、地质、水文和气候条件。
对于那些有几种坝型可建造的地方,则要进行经济比较估算,并根据经济条件来做选择。
安全和运行性能是基本的要求,但是施工时间和材料也常会影响到经济比较。
坝的分类
坝可按照建筑材料(像混凝土或土)来分类。
混凝土坝又进一步分为重力坝、拱坝、支墩坝或这些类型的组合。
土坝则是用土或岩石材料建
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- 水利水电工程 毕业设计 英文翻译 混凝土 重力坝