土木工程专业钢筋混凝土土方工程大学毕业论文英文文献翻译及原文.docx
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土木工程专业钢筋混凝土土方工程大学毕业论文英文文献翻译及原文.docx
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土木工程专业钢筋混凝土土方工程大学毕业论文英文文献翻译及原文
毕业设计(论文)
外文文献翻译
文献、资料中文题目:
钢筋混凝土土方工程
文献、资料英文题目:
文献、资料来源:
文献、资料发表(出版)日期:
院(部):
专业:
土木工程
班级:
姓名:
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指导教师:
翻译日期:
2017.02.14
1外文翻译
1.1ReinforcedConcrete
Plainconcreteisformedfromahardenedmixtureofcement,water,fineaggregate,coarseaggregate(crushedstoneorgravel),air,andoftenotheradmixtures.Theplasticmixisplacedandconsolidatedintheformwork,thencuredtofacilitatetheaccelerationofthechemicalhydrationreactionlfthecement/watermix,resultinginhardenedconcrete.Thefinishedproducthashighcompressivestrength,andlowresistancetotension,suchthatitstensilestrengthisapproximatelyonetenthlfitscompressivestrength.Consequently,tensileandshearreinforcementinthetensileregionsofsectionshastobeprovidedtocompensatefortheweaktensionregionsinthereinforcedconcreteelement.
Itisthisdeviationinthecompositionofareinforcesconcretesectionfromthehomogeneityofstandardwoodorsteelsectionsthatrequiresamodifiedapproachtothebasicprinciplesofstructuraldesign.Thetwocomponentsoftheheterogeneousreinforcedconcretesectionaretobesoarrangedandproportionedthatoptimaluseismadeofthematerialsinvolved.Thisispossiblebecauseconcretecaneasilybegivenanydesiredshapebyplacingandcompactingthewetmixtureoftheconstituentingredientsareproperlyproportioned,thefinishedproductbecomesstrong,durable,and,incombinationwiththereinforcingbars,adaptableforuseasmainmembersofanystructuralsystem.
Thetechniquesnecessaryforplacingconcretedependonthetypeofmembertobecast:
thatis,whetheritisacolumn,abean,awall,aslab,afoundation.amasscolumns,oranextensionofpreviouslyplacedandhardenedconcrete.Forbeams,columns,andwalls,theformsshouldbewelloiledaftercleaningthem,andthereinforcementshouldbeclearedofrustandotherharmfulmaterials.Infoundations,theearthshouldbecompactedandthoroughlymoistenedtoabout6in.indepthtoavoidabsorptionofthemoisturepresentinthewetconcrete.Concreteshouldalwaysbeplacedinhorizontallayerswhicharecompactedbymeansofhighfrequencypower-drivenvibratorsofeithertheimmersionorexternaltype,asthecaserequires,unlessitisplacedbypumping.Itmustbekeptinmind,however,thatovervibrationcanbeharmfulsinceitcouldcausesegregationoftheaggregateandbleedingoftheconcrete.
Hydrationofthecementtakesplaceinthepresenceofmoistureattemperaturesabove50°F.Itisnecessarytomaintainsuchaconditioninorderthatthechemicalhydrationreactioncantakeplace.Ifdryingistoorapid,surfacecrackingtakesplace.Thiswouldresultinreductionofconcretestrengthduetocrackingaswellasthefailuretoattainfullchemicalhydration.
Itisclearthatalargenumberofparametershavetobedealtwithinproportioningareinforcedconcreteelement,suchasgeometricalwidth,depth,areaofreinforcement,steelstrain,concretestrain,steelstress,andsoon.Consequently,trialandadjustmentisnecessaryinthechoiceofconcretesections,withassumptionsbasedonconditionsatsite,availabilityoftheconstituentmaterials,particulardemandsoftheowners,architecturalandheadroomrequirements,theapplicablecodes,andenvironmentalreinforcedconcreteisoftenasite-constructedcomposite,incontrasttothestandardmill-fabricatedbeamandcolumnsectionsinsteelstructures.
Atrialsectionhastobechosenforeachcriticallocationinastructuralsystem.Thetrialsectionhastobeanalyzedtodetermineifitsnominalresistingstrengthisadequatetocarrytheappliedfactoredload.Sincemorethanonetrialisoftennecessarytoarriveattherequiredsection,thefirstdesigninputstepgeneratesintoaseriesoftrial-and-adjustmentanalyses.
Thetrial-and–adjustmentproceduresforthechoiceofaconcretesectionleadtotheconvergenceofanalysisanddesign.Henceeverydesignisananalysisonceatrialsectionischosen.Theavailabilityofhandbooks,charts,andpersonalcomputersandprogramssupportsthisapproachasamoreefficient,compact,andspeedyinstructionalmethodcomparedwiththetraditionalapproachoftreatingtheanalysisofreinforcedconcreteseparatelyfrompuredesign.
1.2Earthwork
Becauseearthmovingmethodsandcostschangemorequicklythanthoseinanyotherbranchofcivilengineering,thisisafieldwheretherearerealopportunitiesfortheenthusiast.In1935mostofthemethodsnowinuseforcarryingandexcavatingearthwithrubber-tyredequipmentdidnotexist.Mostearthwasmovedbynarrowrailtrack,nowrelativelyrare,andthemainmethodsofexcavation,withfaceshovel,backacter,ordraglineorgrab,thoughtheyarestillwidelyusedareonlyafewofthemanycurrentmethods.Tokeephisknowledgeofearthmovingequipmentuptodateanengineermustthereforespendtinestudyingmodernmachines.Generallytheonlyreliableup-to-dateinformationonexcavators,loadersandtransportisobtainablefromthemakers.
Earthworksorearthmovingmeanscuttingintogroundwhereitssurfaceistoohigh(cuts),anddumpingtheearthinotherplaceswherethesurfaceistoolow(fills).Toreduceearthworkcosts,thevolumeofthefillsshouldbeequaltothevolumeofthecutsandwhereverpossiblethecutsshouldbeplacedneartofillsofequalvolumesoastoreducetransportanddoublehandlingofthefill.Thisworkofearthworkdesignfallsontheengineerwholaysouttheroadsinceitisthelayoutoftheearthworkmorethananythingelsewhichdecidesitscheapness.Fromtheavailablemapsahdlevels,theengineeringmusttrytoreachasmanydecisionsaspossibleinthedrawingofficebydrawingcrosssectionsoftheearthwork.Onthesitewhenfurtherinformationbecomesavailablehecanmakechangesinjissectionsandlayout,butthedrawinglfficeworkwillnothavebeenlost.Itwillhavehelpedhimtoreachthebestsolutionintheshortesttime.
Thecheapestwayofmovingearthistotakeitdirectlyoutofthecutanddropitasfillwiththesamemachine.Thisisnotalwayspossible,butwhenitcanbedoneitisideal,beingbothquickandcheap.Draglines,bulldozersandfaceshovelsandothis.Thelargestradiusisobtainedwiththedragline,andthelargesttonnageofearthismovedbythebulldozer,thoughonlyovershortdistances.Thedisadvantagesofthedraglinearethatitmustdigbelowitself,itcannotdigwithforceintocompactedmaterial,itcannotdigonsteepslopws,anditsdumpinganddiggingarenotaccurate.
Faceshovelsarebetweenbulldozersanddraglines,havingalargerradiusofactionthanbulldozersbutlessthandraglines.Theyareanletodigintoaverticalclifffaceinawaywhichwouldbedangeroustorabulldozeroperatorandimpossibleforadragline.Eachpieceofequipmentshouldbeleveloftheirtracksandfordeepdigsincompactmaterialabackacterismostuseful,butitsdumpingradiusisconsiderablylessthanthatofthesameescavatorfittedwithafaceshovel.
Rubber-tyredbowlscrapersareindispensableforfairlyleveldiggingwherethedistanceoftransportistoomuchtoradraglineorfaceshovel.Theycandigthematerialdeeply(butonlybelowthemselves)toafairlyflatsurface,carryithundredsofmetersifneedbe,thendropitandlevelitroughlyduringthedumping.Forharddiggingitisoftenfoundeconomicaltokeepapushertractor(wheeledortracked)onthediggingsite,topusheachscraperasitreturnstodig.Assoonasthescraperisfull,thepushertractorreturnstothebeginningofthedigtoheoptohelpthenestscraper.
Bowlscrapersareoftenextremelypowerfulmachines;manymakersbuildscrapersof8cubicmetersstruckcapacity,whichcarry10m³heaped.Thelargestself-propelledscrapersareof19m³struckcapacity(25m³heaped)andtheyaredrivenbyatractorengineof430horse-powers.
Dumpersareprobablythecommonestrubber-tyredtransportsincetheycanalsoconvenientlybeusedforcarryingconcreteorotherbuildingmaterials.Dumpershavetheearthcontaineroverthefrontaxleonlargerubber-tyredwheels,andthecontainertipsforwardsonmosttypes,thoughinarticulateddumpersthedirectionoftipcanbewidelyvaried.Thesmallestdumpershaveacapacityofabout0.5m³,andthelargeststandardtypesareofabout4.5m³.Specialtypesincludetheself-loadingdumperofupto4m³andthearticulatedtypeofabout0.5m³.Thedistinctionbetweendumpersanddumptrucksmustberemembered.dumperstipforwardsandthedriversitsbehindtheload.Dumptrucksareheavy,strengthenedtippinglorries,thedrivertravelsinfrontlftheloadandtheloadisdumpedbehindhim,sotheyaresometimescalledrear-dumptrucks.
1.3SafetyofStructures
Theprincipalscopeofspecificationsistoprovidegeneralprinciplesandcomputationalmethodsinordertoverifysafetyofstructures.The“safetyfactor”,whichaccordingtomoderntrendsisindependentofthenatureandcombinationofthematerialsused,canusuallybedefinedastheratiobetweentheconditions.Thisratioisalsoproportionaltotheinverseoftheprobability(risk)offailureofthestructure.
Failurehastobeconsiderednotonlyasoverallcollapseofthestructurebutalsoasunserviceabilityor,accordingtoamoreprecise.Commondefinition.Asthereachingofa“limitstate”whichcausestheconstructionnottoaccomplishthetaskitwasdesignedfor.Therearetwocategoriesoflimitstate:
(1)Ultimatelimitsate,whichcorrespondstothehighestvalueoftheload-bearingcapacity.Examplesincludelocalbucklingorglobalinstabilityofthestructure;fai
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