《土木工程專業(yè)英語 第2版》 課件 Unit7 Introduction to Other Branches of Civil Engineering

EnglishforCivilEngineering——Teacher：Prof.ZhengLuE-mail:luzheng111@（SchoolofCivilEngineering,TONGJIUNIVERSITY）Unit7IntroductiontoOtherBranchesofCivilEngineering

Unit7IntroductiontoOtherBranchesofCivilEngineering7.1BridgeEngineering（橋梁工程）

7.1.1ReinforcedConcreteGirderBridges（鋼筋混凝土梁式橋）

7.1.2CableStayedBridges（斜拉橋）

7.1.3SuspensionBridge（懸索橋）7.2UndergroundEngineering（地下工程）7.2.1SeismicDesignandAnalysisofUndergroundStructure7.2.2PerformanceofUndergroundFacilitiesDuringSeismicEvents7.3TrafficEngineering（交通工程）7.3.1Introduction7.3.2TrafficManagementandControl7.4HydraulicEngineering（水利工程）7.4.1Introduction7.4.2TypesofHydraulicStructures7.1BridgeEngineering

7.1.1ReinforcedConcreteGirderBridgesTherawmaterialsofconcrete,consistingofwater,fineaggregate,coarseaggregate,andcement,canbefoundinmostareasoftheworldandcanbemixedtoformavarietyofstructuralshapes.Thegreatavailabilityandflexibilityofconcretematerialandreinforcingbarshavemadethereinforcedconcretebridgeaverycompetitivealternative.Reinforcedconcretebridgesmayconsistofprecastconcreteelements,whicharefabricatedataproductionplantandthentransportedforerectionatthejobsite,orcast-in-placeconcrete,whichisformedandcastdirectlyinitssettinglocation.鋼筋混凝土梁式橋材料搭配與建造過程fineaggregate細(xì)骨料；coarseaggregate粗骨料；cement水泥；precastconcreteelements預(yù)制混凝土構(gòu)件；fabricated制造；cast-in-place現(xiàn)場澆筑Cast-in-placeconcretestructuresareoftenconstructedmonolithicallyandcontinuously.Theyusuallyprovidearelativelylowmaintenancecostandbetterearthquake-resistanceperformance.Cast-in-placeconcretestructures,however,maynotbeagoodchoicewhentheprojectisonafast-trackconstructionscheduleorwhentheavailablefalseworkopeningclearanceislimited.Inthisunit,variousstructuraltypesanddesignconsiderationsforconventionalcast-in-place,reinforcedconcretehighwaygirderbridgearediscussed.鋼筋混凝土梁式橋材料搭配與建造過程Monolithically整體地；maintenancecost維護(hù)費(fèi)用；earthquake-resistanceperformance抗震性能；fast-track

快速；falsework

腳手架7.1BridgeEngineering

1SlabBridges（板橋）Longitudinallyreinforcedslabbridgeshavethesimplestsuperstructure

configurationandtheneatestappearance.Theygenerallyrequiremorereinforcingsteelandstructuralconcretethandogirder-typebridgesofthesamespan.However,thedesigndetailsandformworksareeasierandlessexpensive.Ithasbeenfoundeconomicalforsimplysupportedspansupto9mandforcontinuousspansupto12m.鋼筋混凝土板橋Longitudinally縱向；superstructure

configuration上部結(jié)構(gòu)形狀；girder-typebridges梁式橋7.1BridgeEngineering

2T-BeamBridges（T形梁橋）TheT-beamconstructionconsistsofatransverselyreinforcedslabdeckwhichspansacrosstothelongitudinalsupportgirders.Theserequireamore-complicatedformwork,particularlyforskewedbridges,comparedtotheothersuperstructureforms.T-beambridgesaregenerallymoreeconomicalforspansof12to18m.Thegirderstemthicknessusuallyvariesfrom35to55cmandiscontrolledbytherequiredhorizontalspacingofthepositivemomentreinforcement.Optimumlateralspacingoflongitudinalgirdersistypicallybetween1.8and3.0mforaminimumcostofformworkandstructuralmaterials.However,whereverticalsupportsfortheformworkaredifficultandexpensive,girderspacingcanbeincreasedaccordingly.transverselyreinforcedslabdeck橫向加筋板；formwork模板；skewedbridges斜交橋；

girder大梁；horizontalspacing水平間距；positivemoment正彎矩7.1BridgeEngineering

3Box-GirderBridges（箱梁橋）Box-girderbridgescontaintopdeck,verticalweb,andbottomslabandareoftenusedforspansof15to36mwithgirdersspacedat1.5timesthestructuredepth.Beyondthisrange,itisprobablymoreeconomicaltoconsideradifferenttypeofbridge,suchaspost-tensionedboxgirderorsteelgirdersuperstructure.Thisisbecauseofthemassiveincreaseinvolumeandmaterials.TheycanbeviewedasT-beamstructuresforbothpositiveandnegativemoments.Thehightorsionalstrengthoftheboxgirdermakesitparticularlysuitableforsharpcurvealignment,skewedpiersandabutments,superelevation,andtransitionssuchasinterchangerampstructures.topdeck頂面板；web腹板；post-tensioned后張法；torsionalstrength抗扭強(qiáng)度；skewedpiersandabutments傾斜支柱和臺墩；interchangeramp立交匝道7.1BridgeEngineering

7.1.2CableStayedBridgesTheuseofinclinedstaysasatensionsupporttoabridgedeckwasawell-knownconceptinthenineteenthcenturyandtherearemanyexamples,particularlyusingtheinclinedstayasaddedstiffnesstotheprimarydrapedcablesofthesuspensionbridge.Unfortunately,atthistime,theconceptwasnotwellunderstood.Asitwasnotpossibletotensionthestaystheywouldbecomeslackundervariousloadconditions.Thestructuresoftenhadinadequateresistancetowind-inducedoscillations.Therewereseveralnotablecollapsesofsuchbridges,forexamplethebridgeovertheTweedRiveratDryburgh(Drewry,1832),builtin1817,andcollapsedin1818duringagaleonlysixmonthsafterconstructionwascompleted.AsaresulttheuseofthestayconceptwasabandonedinEngland.Nevertheless,theseideaswereadaptedandimprovedbytheAmericanbridgeengineerRoeblingwhousedcablestaysinconjunctionwiththedrapedsuspensioncableforthedesignofhisbridges.（時間順序介紹斜拉索歷史）inclinedstays斜拉索；bridgedeck橋面板；Slack松弛；wind-inducedoscillations風(fēng)振；gale

狂風(fēng)；

inconjunctionwith連接7.1BridgeEngineering

ThebestknownofRoebling’sbridgesistheBrooklynBridge,completedin1883.Themodernconceptofthecable-stayedbridgewasfirstproposedinpostwarGermany,intheearly1950s,forthereconstructionofanumberofbridgesovertheRiverRhine.Thesebridgesprovedmoreeconomic,formoderatespans,thaneitherthesuspensionorarchbridgeforms.Itprovedverydifficultandexpensiveintheprevailingsoilconditionsofanalluvialfloodplaintoprovidethegravityanchoragesrequiredforthecablesofsuspensionbridges.Similarlyforthearchstructure,whetherdesignedwiththearchthrustcarriedatfoundationlevelorcarriedasatiedarch,substantialfoundationswererequiredtocarrytheselargeheavyspans.Bycomparisonthecable-stayedalternativeshadlightdecksandthetensilecableforceswerepartofaclosedforcesystemwhichbalancedtheseforceswiththecompressionwithinthedeckandpylon.Thusexpensiveexternalgravityanchorageswerenotrequired.（時間順序介紹斜拉索歷史）moderatespans中等跨度；prevailingsoilconditions常見的土壤條件；alluvialfloodplain沖積平原；archthrust拱推力；pylon橋塔7.1BridgeEngineering

7.1.3SuspensionBridgeThescopeofthisunitisrestrictedtoconsiderationoftheclassicalthree-spansuspensionbridgeconfiguration(Fig.7-2),withastiffenedload-carryingdeckstructuresupportedbyearth-anchoredcables.Thebridgemayhavesidespansofdifferinglengthsand,dependingonthesitetopography,thebridgedeckmaybesuspendedeitherinallthreespansorinthemainspanonly,whenthesidespancablesactsimplyasbackstaystothetowers.Bridgeswithunusualspanorcableconfigurations,includingbridgeswithmultiplemainspans,mono-cablebridges,self-anchoredstructures,andhybridpartsuspension/partcable-stayedstructuresarenotconsidered.Evenwiththeabovelimitations,itisnotpossibleinarelativelyshortchaptertoconsiderindetailmanyimportantaspectsofsuspensionbridgedesign–inparticulartheanalysisofcablesandtheaerodynamicdesignrequirements.（懸索結(jié)構(gòu)介紹）three-spansuspensionbridgeconfiguration三跨吊橋結(jié)構(gòu)；earth-anchoredcables地錨；sidespans邊跨；topography地形；mainspans主跨；mono-cable單索；self-anchored自錨式7.1BridgeEngineering

Twoormoremaincablesformedfromhigh-strengthsteelwires,

withastrength-to-weightratioofaroundthreetimesthatofweldablestructuralsteels,andwhichsupportthetraffic-carryingdeckandtransferitsloadingbydirecttensionforcestothesupportingtowersandanchorages.

Asthedeckdeadloadisentirelysupportedbythecable,towersandanchorages,

aneconomicaloveralldesignrequiresthelightestpracticabledeckstructure

whichissupportedfromthemaincablesbyhangersofhigh-strengthwireropesorstrandthatarespacedatregularintervalsthroughoutthespans.懸索橋設(shè)計(jì)原則Weldable焊接的；traffic-carryingdeck橋面板；supportingtowersandanchorages支撐塔架和錨固；deadload恒載；overalldesign總體設(shè)計(jì)；wireropes鋼絲繩；

spacedatregularintervals等間隔放置7.1BridgeEngineering

Withcablesconstructedfromveryhigh-strengthsteelloadedindirecttensionastheirprimaryload-carryingmembers,suspensionbridgesareideallysuitedtolongerspans,andthisisthereforetheprimaryapplicationforthistypeofstructure.Althoughcable-stayedstructureshavemadeconsiderableinroadsintothespanrangepreviouslyconsideredtobethedomainofsuspensionbridges,theseremaintheunchallengedchoiceforspansover1200m.Whenwelldesignedandproportioned,suspensionbridgesarethemostbeautifulofbridges,asthesimplicityofthestructuralarrangement,thenaturalcurveofthemaincables,theslendersuspendeddeckandtowers,produceanaestheticallyattractivestructure.Thisnaturalgracecanalsomakesuspensionbridgesasuitablechoiceforrelativelyshort-spanfootbridgesinsituationswhereanattractiveappearanceisanimportantconsideration.（懸索結(jié)構(gòu)的優(yōu)勢）Inroads侵入，損耗；directtension直接受拉；naturalcurve自然曲線；aestheticallyattractive美觀，吸引人7.1BridgeEngineering

7.2.1SeismicDesignandAnalysisofUndergroundStructureThisreportfocusesonrelativelylargeundergroundfacilitiescommonlyusedinurbanareas.Thisincludeslarge-diametertunnels,cut-and-coverstructuresandportalstructures(Fig.7-3).Thisreportdoesnotdiscusspipelinesorsewerlines,nordoesitspecificallydiscussissuesrelatedtodeepchamberssuchashydropowerplants,nuclearwasterepositories,minechambers,andprotectivestructures,thoughmanyofthedesignmethodsandanalysesdescribedareapplicabletothedesignofthesedeepchambers.本報(bào)告重點(diǎn)內(nèi)容

Portal洞門；pipelines管道；sewer下水道；chambers內(nèi)庭；hydropower水力發(fā)電；repositories貯藏室7.2UndergroundEngineering

Large-diametertunnelsarelinearundergroundstructuresinwhichthelengthismuchlargerthanthecross-sectionaldimension.Thesestructurescanbegroupedintothreebroadcategories,eachhavingdistinctdesignfeaturesandconstructionmethods:(1)boredorminedtunnels;(2)cut-and-covertunnels;and(3)immersedtubetunnels.Thesetunnelsarecommonlyusedformetrostructures,high-waytunnels,andlargewaterandsewagetransportationducts.大直徑隧道分類Categories種類；distinct不同的；immersed沉入的；metro地鐵；sewage下水道7.2UndergroundEngineering

Cut-and-coverstructuresarethoseinwhichanopenexcavationismade,thestructureisconstructed,andfillisplacedoverthefinishedstructure.Thismethodistypicallyusedfortunnelswithrectangularcross-sectionsandonlyforrelativelyshallowtunnels(<15mofoverburden).Examplesofthesestructuresincludesubwaystations,portalstructuresandhighwaytunnels.Immersedtubetunnelsaresometimesemployedtotraverseabodyofwater.Thismethodinvolvesconstructingsectionsofthestructureinadrydock,thenmovingthesesections,sinkingthemintopositionandballastingoranchoringthetubesinplace.大直徑隧道建造方法excavation挖掘；shallow淺；overburden覆蓋層；traverse移動；

sinking下稱7.2UndergroundEngineering

Thisreportdoesnotcoverissuesrelatedtostaticdesign,althoughstaticdesignprovisionsforundergroundstructuresoftenprovidesufficientseismicresistanceunderlowlevelsofgroundshaking.Thereportdoesnotdiscussstructuraldesigndetailsandreinforcementrequirementsinconcreteorsteelliningsforundergroundstructures.Thereportbrieflydescribesissuesrelatedtoseismicdesignassociatedwithgroundfailuresuchasliquefaction,slopestabilityandfaultcrossings,butdoesnotprovideathoroughtreatmentofthesesubjects.

Thereaderisencouragedtoreviewotherliteratureonthesetopicstoensurethatrelevantdesignissuesareadequatelyaddressed.本報(bào)告沒有涉及到的內(nèi)容provisions規(guī)范；

briefly簡要的；liquefaction液化；fault斷層；

thorough徹底的；literature文獻(xiàn)7.2UndergroundEngineering

7.2.2PerformanceofUndergroundFacilitiesDuringSeismicEventsTunnelsaremorestableunderasymmetricload,whichimprovesground-lininginteraction.Improvingthetunnelliningbyplacingthickerandstiffersectionswithoutstabilizingsurroundingpoorgroundmayresultinexcessseismicforcesinthelining.Backfillingwithnon-cyclicallymobilematerialandrock-stabilizingmeasuresmayimprovethesafetyandstabilityofshallowtunnels.隧道在地震作用下的性能Symmetric對稱的；excess過度的；Backfilling回填；stability穩(wěn)定性7.2UndergroundEngineering

The1995Hyogoken-NambuEarthquakecausedamajorcollapseoftheDaikaisubwaystationinKobe,Japan.Thestationdesignin1962didnotincludespecificseismicprovisions.Itrepresentsthefirstmodernundergroundstructuretofailduringaseismicevent.Fig.7-4showsthecollapseexperiencedbythecentercolumnsofthestation,whichwasaccompaniedbythecollapseoftheceilingslabandthesettlementofthesoilcoverbymorethan2.5m.日本神戶地鐵站1995年發(fā)生的倒塌事故collapse倒塌；

modern現(xiàn)代的；accompanied伴隨；ceiling天花板；settlement沉降7.2UndergroundEngineering

Duringtheearthquake,transversewallsattheendsofthestationandatareaswherethestationchangedwidthactedasshearwallsinresistingcollapseofthestructure.Thesewallssufferedsignificantcracking,buttheinteriorcolumnsintheseregionsdidnotsufferasmuchdamageunderthehorizontalshaking.Inregionswithnotransversewalls,collapseofthecentercolumnscausedtheceilingslabtokinkandcracks150-250mmwideappearedinthelongitudinaldirection.Therewasalsosignificantseparationatsomeconstructionjoints,andcorrespondingwaterleakagethroughcracks.Fewcracks,ifany,wereobservedinthebaseslab.地鐵站倒塌的詳細(xì)情況transverse橫向的；

significant重大的；interior內(nèi)部的；longitudinal縱向的；

separation分離；joints節(jié)點(diǎn)；leakage泄漏7.2UndergroundEngineering

Itislikelythattherelativedisplacementbetweenthebaseandceilinglevelsduetosubsoilmovementcreatedthedestructivehorizontalforce.Thistypeofmovementmayhaveminoreffectinasmallstructure,butinalargeonesuchasasubwaystationitcanbesignificant.Thenon-linearbehaviorofthesubsoilprofilemayalsobesignificant.Itisfurtherhypothesizedthatthethicknessoftheoverburdensoilaffectedtheextentofdamagebetweensectionsofthestationbyaddinginertialforcetothestructure.

Othersattributethefailuretohighlevelsofverticalacceleration.下層土運(yùn)動引起的水平力是破壞性的destructive破壞性的;profile剖面；hypothesized假定；attribute把······歸于7.2UndergroundEngineering

SeveralhighwaytunnelswerelocatedwithinthezoneheavilyaffectedbytheSeptember21,1999ChiChiearthquake(ML7.3)incentralTaiwan.Thesearelargehorseshoeshapedtunnelsinrock.Allthetunnelsinspectedbythefirstauthorwereintactwithoutanyvisiblesignsofdamage.ThemaindamageoccurredattunnelportalsbecauseofslopeinstabilityasillustratedinFig.7-6.Minorcrackingandspallingwasobservedinsometunnellining.OnetunnelpassingthroughtheChelungpufaultwasshutdownbecauseofa4-mfaultmovement.NodamagewasreportedintheTaipeisubway,whichislocatedover100kmfromtherupturedfaultzone.臺灣的地下結(jié)構(gòu)在地震中的性能horseshoe馬蹄型;inspected檢查；intact完整的；spalling剝落；ruptured破裂的7.2UndergroundEngineering

TheAugust17,1999KocealiearthquakewasreportedtohavehadminimalimpactontheBolutunnel.Theclosurerateofonemonitoringstationwasreportedtohavetemporarilyincreasedforaperiodofapproximately1week,thenbecamestableagain.Additionally,severalhairlinecracks,whichhadpreviouslybeenobservedinthefinallining,werebeingcontinuouslymonitoredforadditionalmovementandshowednomovementduetotheearthquake.

TheNovember12,1999earthquakecausedthecollapseofbothtunnels300mfromtheireasternportal.Atthetimeoftheearthquake,a800-msectionhadbeenexcavated,anda300-msectionofunreinforcedconcretelininghadbeencompleted.Thecollapsetookplaceinclaygaugematerialintheunfinishedsectionofthetunnel.Thesectionwascoveredwithshotcrete(sprayedconcrete)andhadboltanchors.土耳其的地下結(jié)構(gòu)在地震中的性能closure關(guān)閉；temporarily暫時；hairline極細(xì)的；excavated挖掘；shotcrete噴漿混凝土7.2UndergroundEngineering

TheDaikaisubwaystationcollapsewasthefirstcollapseofanurbanundergroundstructureduetoearthquakeforces,ratherthangroundinstability.UndergroundstructuresintheUShaveexperiencedlimiteddamageduringtheLomaPrietaandNorthridgeearthquakes,buttheshakinglevelshavebeenmuchlowerthanthemaximumanticipatedevents.Greaterlevelsofdamagecanbeexpectedduringthesemaximumevents.StationcollapseandanticipatedstrongmotionsinmajorUSurbanareasraisegreatconcernsregardingtheperformanceofundergroundstructures.Itisthereforenecessarytoexplicitlyaccountforseismicloadinginthedesignofundergroundstructures.地下結(jié)構(gòu)在地震中性能總結(jié)Instability不穩(wěn)定性；

anticipated預(yù)期的；explicitly明確的7.2UndergroundEngineering

7.3TrafficEngineering

7.3.1IntroductionTrafficcanbedefinedasthemovementofpedestriansandgoodsalongaroute,andinthe21stcenturythebiggestproblemandchallengeforthetrafficengineerisoftentheimbalancebetweentheamountoftrafficandthecapacityoftheroute,leadingtocongestion.Trafficcongestionisnotanewphenomenon.RomanhistoryrecordsthatthestreetsofRomeweresocloggedwithtrafficthatatleastoneemperorwasforcedtoissueaproclamationthreateningthedeathpenaltytothosewhosechariotsandcartsblockedtheway.Morerecentlypicturesofourmoderncitiestakenattheturnofthecenturyshowstreetscloggedwithtraffic.Thedictionarydescribes’traffic’asthetransportationofgoods,comingandgoingofpersonsorgoodsbyroad,rail,air,etc.Oftenincommonusageweforgetthiswiderdefinitionandcolloquiallyequatethewordwithmotorisedroadtraffic,totheexclusionofpedestriansandevencyclists.Trafficengineeringisconcernedwiththewiderdefinitionoftraffic.congestion擁擠；proclamation

公告；chariots二輪戰(zhàn)車；carts

二輪馬車；colloquially

口語地；Thedefinitionremainsvalidtodaybuttherehasclearlybeenachangeintheemphasisintheroleoftheengineerinthetime.Inthe1970sthecarwasseenasthefutureandthefocuswasverymuch‘predictandprovide’.Trafficengineersweretaskedwithincreasingthecapacityofthehighwaysystemtoaccommodatewhatseemedandendlessgrowthinmotortraffic,oftenattheexpenseofotherroadusers.Roadcapacityimprovementswereoftenachievedattheexpenseofpedestrianfreedomofmovement,pushingpedestrianstobridgesandunderpassessothatthesurfacecouldbegivenovertothecar.However,itisnowgenerally,butbynomeansuniversallyrecognizedthatwewillneverbeabletoaccommodateunconstrainedtraveldemandbycarandsoincreasinglytrafficengineeringhasbecomefocusedonsharingspaceandensuringthatmoresustainableformsoftransportsuchaswalkingandcyclingareadequatelycateredfor.交通定義的變化weretaskedwith受…挑戰(zhàn)；unconstrained無約束的7.3TrafficEngineering

Tarhasbeenusedformanyyearsinroadconstructionbothasabinderformacadamandasasurfacedressinginitiallyonwater-boundroads.RoadtaristodayspecifiedinBS761bythefollowingdefinition:‘tarforuseinroadworkispreparedentirelyfromcrudetarsproducedwhollyorsubstantiallyasaby-productinthecarbonisationofcoalatabove600°Cinexternallyheatedretortsorcokeovens’.公路路面材料介紹Tar柏油；binder

粘合劑；macadam碎石；crude粗糙的；天然的；carbonization碳化作用；retorts曲頸瓶；cokeovens

煉焦?fàn)t7.3TrafficEngineering

Concretepavementsareconstructedinavarietyofformsbyseveraldifferentconstructionmethods.Theymaybereinforcedorunreinforced;ifreinforcedthesteelmaytaketheformofindividualbarsorweldedmesh.Theslabsmaycontainseveraldifferenttypesofjointortheymaybeunjointedorcontinuous.Constructionmaybecarriedoutbytheconventionalside-formprocessusingaconcretingtrainwithmanydifferingunits,oroneofseveralformsofslip-formpavermaybeemployedoperatingwithaminimumofadditionalequipment.混凝土路面施工weldedmesh焊接網(wǎng)；slabs

板材；conventional傳統(tǒng)的；7.3TrafficEngineering

TheimportanceofadequatedrainagewasrealisedbyRomanroadbuilders,butafterthedeclineoftheRomanEmpirethestandardofhighwayconstructioninEuropedeclinedandplanneddrainagebecamealmostnon-existent.Withtheadventofindustrialisationincreasingattentionwaspaidtotheremovalofsurfacewaterandtheloweringofthewater-tablebeneaththepavement.IntheUnitedKingdomthepioneerroad-buildingofTelfordandMacadamlaidstressontheincorporationofacamberorcrownintotheroadsothatsurfacewatercouldbequicklyremoved.Increasingurbandevelopmentmadeopenditchesinappropriateandledtotheincreasinguseofroadgulleysconnectedtoroadsewersasthemeansofremovingsurfacewater.Improvementsinthequalityofroadmaterialshaveresultedinimperviouspavements,makingtheproblemofsub-soilusuallygreatestinthecuttings,wherecut-offdrainageisrequired.路面排水系統(tǒng)介紹industrialisation工業(yè)化；camber

弧形；ditches溝渠；gulleys

集水口；imperviouspavements

不透水路面；7.3TrafficEngineering

Asiteinvestigationisanessentialfirststepinthedesignofanyhighwayonanewlocation.Theinformationobtainedbythesurveyassistsinlocatingthehighwaytoavoidadversegeologicalconditionsandindesigningearthworks,pavementthickness,drainageworksandbridgefoundations.實(shí)地勘測adversegeologicalconditions不良地質(zhì)條件；earthworks

土方工程；7.3TrafficEngineering

Withthedrainageworkscompletedandallservicesandductscrossingthecarriage-wayinplace,theformationmaybesealedtoprotectthesubgradefromexcessivemoisturechanges.Thisisbecauseacohesivesubgradewhichhasbecomeexcessivelydryduetoevaporationduringadryconstructionseasonmayswellwithsubsequentincreasesinmoisturecontent,resultingindifferentialmovementofthepavement.Ontheotherhandasubgradethathasbecomeexcessivelywetisdifficulttocompactandtooverlaywithsub-basematerial.鋪面施工formation地層；duct管道；seal

密封；subgrade路基；

excessive過度的；cohesive有粘著力的；evaporation

蒸發(fā)；swellwith膨脹，充滿；7.3TrafficEngineering

Thetwentiethcenturyhasseenaconsiderableimprovementinthematerialsandconstructionaltechniquesusedforhighwaypavements.Thishasresultedinadramaticincreaseinthelifeofapavementfromtheperiodwhenanannualsurfacedressingwasnecessarytomaintaintheshapeofthepavementtothepresenttimewhendesignlivesoffromfivetotwentyyearsarecommonforheavilytraffickedhighways.路面養(yǎng)護(hù)介紹dramatic急劇的；trafficked

行車的；7.3TrafficEngineering

Everytripbyavehicleresultsinaparkingactattheendofthetrip.Theimportanceofparkingcanperhapsbeillustratedbythefactthat,onaverage,acarintheUKisparkedforabout23hoursaday.Thevehiclemaybeparkedonthestreetoroff-streetinacar/lorry/cyclepark,orinaprivategarage.Howvehiclesarriveanddepartfromtheseparkingplaces,howlongtheystayandunderwhatcircumstancesdefinevehiculartrafficandindeedsomepedestriantrafficontheroadsandhelptodeterminewhatmeasuresarerequiredtomeetormanagethedemand.Therefore,itisveryimportanttoobtainanobjectiveandunbiasedunderstandingofthisactivitybyproperlyconstructedandconductedsurveys.停車情況調(diào)查的必要性unbiased公正的；7.3TrafficEngineering

Theestimationoftraveldemandisafundamentalpartoftrafficengineeringdesignwork.Thekeyquestionsarehowmucheffortneedstobeexpendedinestimatingdemandandwhatmethodshouldbeadopted.Theanswersdependonthenatureofthedesignissues.Forexample,aminortrafficmanagementdesigntoimproveroadsafetyoveralengthofroadininnerLondonwheretrafficflowshavebeenstableformanyyearswillrequirelittlemorethanasurveyofexistingtraffic.Thereverseistrueofaproposalforanewroadwaytoassistregenerationinanoldurbanareawheredesignwilldependonestimatingthenewtrafficlikelytobeattractedtousethenewroad.出行需求估計(jì)littlemorethan僅僅是；regeneration

重建；7.3TrafficEngineering

Thetermcapacitywhenreferringtoahighwaylinkorjunctionisitsabilitytocarry,accommodateorhandletrafficflow.Traditionally,capacityhasbeenexpressedinnumbersofvehiclesorpassengercarunits(PCU).(Vehiclesvaryintheirperformanceandtheamountofroadspacetheyoccupy.ThebasicunitisthepassengercarandothervehiclesarecountedastheirPCUequivalent,e.g.abusmightbe3PCUsandapedalcycle0.1PCU.)Inrecentyearspublictransportoperatorshaveappliedpressuretoconsiderhighwaysintermsoftheirpassenger-handlingcapacityandthusgiveagreateremphasistothebenefitsofusinghighoccupancyvehicles,suchasbusesortrams.通行能力分析operators經(jīng)營者；occupancy

占用；7.3TrafficEngineering

Trafficsignalsareusedtoregulateandcontrolconflictsbetweenopposingvehicularorpedestriantrafficmovements.Withouttheuseofsignalsatsomesitesthemajorflowwoulddominatethejunction,makingentriesfromtheminorroadimpossibleorverydangerous.Atothersitestheminorroadmightinterferewiththeflowofmajorroadtraffictosuchanextentthatexcessivecongestionwouldoccur.Trafficsignalscannotonlyimprovejunctioncapacity,butcanalsoimproveroadsafety.Thetrafficengineerwillneedtokno