苏港万吨级码头结构设计英文翻译.docx
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苏港万吨级码头结构设计英文翻译.docx
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苏港万吨级码头结构设计英文翻译
CivilEngineering
Abstract:
Thecivilengineermayworkinresearch,design,constructionsupervision,maintenance,oreveninmanagement.Eachoftheseareasinvolvesdifferentdutiesanddifferentuseoftheengineer’sknowledgeandexperience.
1.CareersinCivilEngineering
Engineeringisaprofession,whichmeansthatanengineermusthaveaspecializeduniversity
education.Manycountriesalsorequireengineeringgraduatestopassanexamination,similartothebarexaminationsforalawyer,beforetheycanstartontheircareers.
Intheuniversity,mathematics,physics,andchemistryareconsideredveryimportantthroughouttheengineeringcurriculum,particularlyinthefirsttwoorthreeyears.Mathematics,ofcourse,isveryimportantinengineering,soitisgreatlystressed.Today,mathematicsincludescoursesinstatistics,whichdealswithgathering,classifying,andusingnumericaldata,orpiecesofinformation.Animportantpartofstatisticalmathematicsisprobability,whichdealswithwhatmayhappenwhentherearedifferentfactorsthatcanchangetheresultsofaproblem.Beforetheconstructionofabridgeisbegun,forexample,astatisticalstudyismadeoftheamountoftrafficthebridgewillbeexpectedtocontrol.Inthedesignofthebridge,factorssuchaswaterpressureonthefoundations,theeffectsofdifferentwindforces,andmanyotherfactorsmustbeconsidered.
Becauseagreatdealofcalculationisinvolvedinsolvingtheseproblems,computerprogrammingisnowincludedinalmostallengineeringcurricula.Computers,ofcourse,cansolvemanyproblemsinvolvingcalculationswithgreaterspeedandaccuracythanahumanbeingcan.Butcomputersareuselessunlesstheyaregivenclearandaccurateinstructionsandinformation---inotherwords,agoodprogram.
Inspiteoftheimportanceoftechnicalsubjectsintheengineeringcurriculum,acurrenttrendistorequirestudentstotakecoursesinthesocialsciencesandthelanguagearts.Wehavealreadydiscussedtherelationshipbetweenengineeringandsociety.Itis,therefore,sufficienttosayagainthattheworkdonebyanengineeraffectssocietyinmanydifferentandimportantwaysthatheorsheshouldunderstand.Anengineeralsoneedsagoodcommandoflanguagetobeabletopreparereportsthatareclearandpersuasive.Anengineerdoingresearchworkwillneedtobeabletowriteuphisorherfindingsforpublications.
Thelasttwoyearsofanengineeringprogramincludesubjectswithinthestudent’sfieldofspecialization.Forthestudentwhoispreparingtobecomeacivilengineer,thespecializedcoursesmaydealwithsuchsubjectsassoilmechanics,orhydraulics.
Intoday’ssociety,peoplewhohavetechnicaltrainingare,ofcourse,indemand.Youngengineersmaychoosetogointoenvironmentalengineering,forexample.Theymaychooseconstructionfirmsthatspecializesinhighwaywork.Theymayprefertoworkwithoneofthegovernmentagenciesthatdealswithwaterresources.Indeed,choicesaremayandvaried.
Whentheyoungengineerhasfinallystartedrealpractice,thetheoreticalknowledgeacquiredintheuniversitymustbeapplied.Heorshewillprobablyworkwithateamofengineersatthebeginning.Thus,on-the-jobtrainingcanbeacquiredthatwilldemonstratehisorherabilitytotranslatetheoryintopractice.
Thecivilengineermayworkinresearch,design,constructionsupervision,maintenance,oreveninmanagement.Eachoftheseareasinvolvesdifferentdutiesanddifferentuseoftheengineer’sknowledgeandexperience.
2.SoilMechanics
Grainsizeisthebasisofsoilmechanics,sinceitisthiswhichdecideswhetherasoilisfrictionalorcohesive,asandoraclay.Startingwiththelargestsizes,bouldersarelargerthan10cm,cobblesarefrom5to10cm,gravelorballastisfromabout5cmto5mm,gritisfromabout5mmto2mm,sandisfrom2mmto0.06mm.Allthesesoilsarefrictional,beingcoarseandthusnon-cohesive.Theirstabilitydependsontheirinternalfriction.Forthecohesiveornon-frictionalsoilsthetwomaininternationallyacceptedsizelimitsare:
siltfrom0.02mmto0.002mm,andclayforallfinermaterial.Thereare,ofcourse,manysiltyclaysandclayeysilts.
Everylargecivilengineeringjobstartswithasoilmechanicssurveyinitsearlystages.Thefirstvisitonfootwillshowwhetherthesitemightbesuitable,inotherwords,whethermoneyshouldbespentonsendingsoil-samplingequipmentouttoit.Thesoilsamplesandthelaboratoryresultsobtainedfromthetriaxialtests,sheartestsandsoonwillshowatwhatdepththesoilislikelytobestrongenoughtotaketherequiredload.Foramasonryorsteelstructure,thisiswherethesoilmechanicssurveywillend,havingrarelycostmorethan2percentofthestructurecost.
Generally,thestrengthofasoilincreaseswithdepth.Butitcanhappenthatitbecomesweakerwithdepth.Therefore,inchoosingthefoundationpressureandlevelforthissortofsoil,aknowledgeofsoilmechanicsisessentialisessential,sincethiswillgiveanideaofthelikelysettlements.
Thereare,however,severalothercausesofsettlementapartfromconsolidationduetoload.Thesecausesareincalculableandmustbecarefullyguardedagainst.Theyincludefrostaction,chemicalchangeinthesoil,undergrounderosionbyflowingwater,reductionofthegroundwaterlevel,nearbyconstructionoftunnelsorvibratingmachinerysuchasvehicles,
Staticloadcancauseelasticorplasticsettlement,consolidationsettlementbeingpermanent.However,whenplasticflowismentionedinEnglish,itgenerallymeansthefailureofasoilbyoverloadinshear.Consolidationsettlementoccursmainlyinclaysorsilts.
Fromdynamicloadalonethecommonestsettlementsarefoundinsandsorgravels,causedbytrafficorothervibration,piledrivingorotherearthshocks.Adropinthegroundwaterlevelwilloftencausethesoiltoshrinkandarisemaycauseexpansionofthesoil.Groundwaterislowreredbythedrainagewhichcanbecausedbyanydeepexcavation.TheshrinkagewhichcanoccurwithdryingiswellshownbytheclayunderlyingMexicoCity,avolcanicash.Aftersevenweeksdryingthisclayshrinksto6.4percentofitsinitialvolume.Itisanunusualclaywiththeveryhighvoidsratioof93.6/6.4=14.6.
Undergrounderosionistheremovalofsolids,usuallyfines,fromthesoilbytheflowofundergroundwater.Thesolidscanberemovedassolidsorinsolution,thoughonlyafewrocksaresolubleenoughtoberemovedinthisway.Rocksaltisthecommonestexampleofasolublerock.Potassiumsaltsalsoaresoluble.
Thepermeabilityofasoilisimportantforcalculationsofundergroundflow,forexampleofoilorwatertoawell,orofwaterintoatrenchdugforafoundation,orofwaterthroughanearthdam.Oftheloosesoilswhichcanbedugwithaspade,claysaretheleastpermeable,siltsslightlymore,sandsyetmore,andgravelsevenmore.Inotherwords,thepermeabilityisindirectproportiontothegrainsizeofthesoil.
Whenawellisbeingpumped,thewaterflowstowardsitfromeverydirectionandthegroundwatersurfacearounditsinks.Asthedistancefromthewellincreases,thewatertableisloweredratherless,sothataroundthewellitbecomesshapedlikeafunnel,thoughitisusuallycalledaconeofdepression.
3.Foundations
Foundationsarebasesplacedonthegroundsoastospreadaverticalloadoverit.Baseswhichcarryhorizontalloadareusuallycalledabutments.
Afoundationmaybebuiltinoneofmanydifferentmaterials.Itmaybeoftimberorofsteeljoistsencasedinconcrete,ofreinforcedconcreteorplainconcretewithoutreinforcement,orforabreakwaterintheseamerelyofrocktippedfromabarge.Structuresbuiltonstrongrockgenerallyneednofoundationsincerockisusuallyasstrongasconcrete,andgoesmuchdeeper.Allthatisneededonrockisalittleconcreteormortartomakethesurfacelevel.
Oneofthecommonestfoundationsisthatforaconcretecolumnorasteelstanchion.Itisgenerallydesignedforthesamemaximumloadasthecolumn,andusuallyisanindependentfoundation.Wherethepadsinonerowbecomesolargethattheynearlytouch,itisconvenienttojointhemintoacontinuousfoundationwhichgenerallywillbecheapertodigandtoconcretethanthesamefoundationsbuiltseparatelyaspads.
Combinedfootingsarethoseinwhichthepadswouldalsobesolargethatnearlytouch,butunlikestripfootings,theymaycarrytheloadformmorethanonerowofcolumns.Thefinaldevelopmentofthecombinedfootingistheraftfoundationinwhichallthepadsarecombinedintoonereinforcedconcreteslabwhichmayvaryinthickness,butisusuallyofthesamethicknessthroughoutitsarea.
Thedesignofamulti-storeybuildingoncompressiblesoilisdifficultandthereforeextremelyinteresting.Compressiblesoilsarelikeasponge,sinkingmostwherethepressureisgreatestandtheloadislargest.Thusevenifallthefoundationsaredesignedforthesamebearingpressure,say1ton/m2,thelargestfoundationwillsinkthemostbecauseithasthelargestload.Acorrectfoundationdesignwillthereforeapplyahigherbearingpressuretothesmallerfoundationsandaloweronetothelargerfoundations.Theexactcalculationofthesedifferentbearingpressuresisextremelydifficult.Butatleastthisisnowtheaimoffoundationdesigners.
Itmustherebesaidthatthefoundationdesignerbeforehestartsthedesignshouldknowthesafebearingpressureswhichareabvisableateverylevelpossibleforthefoundation.Hewillusuallyobtainthesefiguresfromtheorganizationwhichmakesthesoilmechanicssurveyforthesite.
Formostmulti-storeybu
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