公路路面毕业论文中英文资料外文翻译文献

中英文资料公路路面中英文资料外文翻译文献PavementHighwaypavementsaredividedintotwomaincategories:rigitandflexible.ThewearingsurfaceofarigidpavementisusuallyconstructedofPortlandcementconcretesuchthatitactslikeabeamoveranyirregularitiesintheunderlyingsupportingmaterial.Thewearingsurfaceofflexiblepavements,ontheotherhand,isusuallyconstructedofbituminousmaterialsuchthattheyremainincontactwiththeunderlyingmaterialevenwhenminorirregularitiesoccur.Flexiblepavementsusuallyconsistofabituminoussurfaceunderlaidwithalayerofgranularmaterialandalayerofasuitablemixtureofcoarseandfinematerials.CoarseaggregatesFineaggregatesTrafficloadsaretransferredbythewearingsurfacetotheunderlyingsupportingmaterialsthroughtheinterlockingofaggregates,thefrictionaleffectofthegranularmaterials,andthecohesionofthefinematerials.Flexiblepavementsarefurtherdividedintothreesubgroups:hightype,intermediatetype,andlowtype.High-typepavementshavewearingsurfacesthatadequatelysupporttheexpectedtrafficloadwithoutvisibledistressduetofatigueandarenotsusceptibletoweatherconditions.Intermediate-typepavementshavewearingsurfacesthatrangefromsurfacetreatedtothosewithqualitiesjustbelowthatofhigh-typepavements.Low-typepavementsareusedmainlyforlow-costroadsandhavewearingsurfacesthatrangefromuntreatedtoloosenaturalmaterialstosurface-treatedearth.Thecomponentsofaflexiblepavementincludethesubgradeorprepared—1—中英文资料roadbed,thesubbase,basecourse,andthesurfacecourse(Fig.11.1).UppersurfacecourseMiddlesurfacecourseLowersurfacecourseTheperformanceofthepavementdependsonthesatisfactoryperformanceofeachcomponent,whichrequiresproperevaluationofthepropertiesofeachcomponentseparately.Thesubgradeisusuallythenaturalmateriallocatedalongthehorizontalalignmentofthepavementandservesasthefoundationofthepavementstructure.Thesubgrademayalsoconsistofalayerofselectedborrowmaterials,wellcompactedtoprescribedspecifications.CompactingplantCompactiondeviceCompactnessItmaybenecessarytotreatthesubgradematerialtoachievecertainstrengthpropertiesrequiredforthetypeofpavementbeingconstructed.Locatedimmediatelyabovethesubgrade,thesubbasecomponentconsistsofasuperiorqualitytothatwhichgenerallyisusedforsubgradeconstruction.Therequirementsforsubbasematerialsareusuallygivenintermsofthegradation,plasticcharacteristics,andstrength.Whenthequalityofthesubgradematerialmeetstherequirementsofthesubbasematerial,thesubbasecomponentmaybeomitted.Incaseswheresuitablesubbasematerialisnotreadilyavailable,theavailablematerialcanbetreatedwithothermaterialstoachievethenecessaryproperties.Thisprocessoftreatingsoilstoimprovetheirengineeringpropertiesisknowasstabilization.Thebasecourseliesimmediatelyabovethesubbase.Itisplacedimmediatelyabovethesubgradeifasubbasecourseisnotused.Thiscourseusuallyconsistsofgranularmaterialssuchascrushedstone,crushedoruncrushed.Thespecificationsforbasecoursematerialsusuallyincludestricterrequirementsthanthoseforsubbasematerials,particularlywithrespecttotheirplasticity,gradation,andstrength.MaterialsthatdonothavetherequiredpropertiescanbeusedasbasematerialsiftheyareproperlystabilizedwithPortlandcement,asphalt,orlime.Insomecases,high-qualitybasecoursematerialsmayalsobetreatedwithasphaltorPortlandcementtoimprovethestiffnesscharacteristicsofheavy-dutypavementsThesurfacecourseistheuppercourseoftheroadpavementandisconstructedimmediatelyabovethebasecourse.Thesurfacecourseinflexiblepavementusuallyconsistsofamixtureofmineralaggregatesandasphalticmaterials.Itshouldbecapableofwithstandinghightirepressures,resistingtheabrasiveforcesduetotraffic,providingaskid-resistantdrivingsurface,andpreventingthe—2—中英文资料penetrationofsurfacewaterintotheunderlyinglayers.Thethicknessofthewearingsurfacecanvaryfrom3in.tomorethan6in.（inch2.54cm）,dependingontheexpectedtrafficonthepavement.Itwasshownthatthequalityofthesurfacecourseofaflexiblepavementdependsonthemixdesignoftheasphaltconcreteused.Rigidhighwaypavementsusuallyareconstructedtocarryheavytrafficloads,althoughtheyhavebeenusedforresidentialandlocalroads.Properlydesignedandconstructedrigidpavementshavelongservicelivesandusuallyarelessexpensivetomaintainthantheflexiblepavements.ThePortlandcementconcretecommonlyusedforrigidpavementsconsistsofPortlandcement,coarseaggregate,fineaggregate,andwater.Steelreinforcingrodsmayormaynotbeused,dependingonthetypeofpavementbeingconstructed.Rigidhighwaypavementsbedividedintothreegeneraltype:plainconcretepavements,simplyreinforcedconcretepavements,andcontinuouslyreinforcedconcretepavement.Thedefinitionofeachpavementtypeisrelatedtotheamountofreinforcementused.Plainconcretepavementhasnotemperaturesteelordowelsforloadtransfer.However,steeltiebarsareoftenusedtoprovideahingeeffectatlongitudinaljointsandtopreventtheopeningofthesejoints.Plainconcretepavementsareusedmainlyonlow-volumehighwaysorwhencement-stabilizedsoilsareusedassubbase.Jointsareplacedatrelativelyshorterdistances(10to20ft)thanwiththeothertypesofconcretepavementstoreducetheamountofcracking.Insomecase,thetransversejointsofplainconcretepavementsareskewedabout4to5ftinplan,suchthatonlyonewheelofavehiclepassesthroughthejointatatime.Thishelpstoprovideasmootherride.Simplyreinforcedconcretepavementshavedowelsforthetransferoftrafficloadsacrossjoints,withthesejointsspacedatlargerdistances,rangingfrom30to100ft.Temperaturesteelisusedthroughouttheslab,withtheamountdependentonthelengthoftheslab.Tiebarsarealsocommonlyusedinlongitudinaljoints.5~10cm填缝料3~4cmh/2涂沥青传力杆h/2横向施工缝构造—3—中英文资料5~10cm3~4cm填缝料h/2h/2拉杆10cm平缝加拉杆型Continuouslyreinforcedconcretepavementshavenotransversejoints,exceptconstructionjointsorexpansionjointswhentheyarenecessaryatspecificpositions,suchasatbridges.Thesepavementshavearelativelyhighpercentageofsteel,withtheminimumusuallyat0.6percentofthecrosssectionoftheslab.Theyalsocontaintiebarsacrossthelongitudinaljoints.BituminousSurfaceCoursesThebituminoussurfacecoursehastoprovideresistancetotheeffectsofrepeatedloadingbytyresandtotheeffectsoftheenvironment.Inaddition,itmustofferadequateskidresistanceinwetweatheraswellascomfortablevehicleride.Itmustalsoberesistanttoruttingandtocracking.Itisalsodesirablethatsurfacecourseisimpermeable,exceptinthecaseofporousasphalt.Hotrolledasphalt(HRA)isagapgradedmaterialwithlesscoarseaggregate.Infactitisessentiallyabitumen/fineaggregate/fillermortarintowhichsomecoarseaggregateisplaced.Themechanicalpropertiesaredominatedbythoseofthemortar.ThismaterialhasbeenextensivelyusedasthewearingcourseonmajorroadintheUK,thoughitsusehasrecentlydeclinedasnewmaterialshavebeenintroduced.Itprovidesadurablelayerwithgoodresistancetocrackingandonewhichisrelativelyeasytocompact.Thecoarseaggregatecontentislow(typically30%)whichresultsinthecompactedmixturehavingasmoothsurface.Accordingly,theskidresistanceisinadequateandprecoatedchippingsarerolledintothesurfaceatthetimeoflayingtocorrectthisdeficiency.InScotland,HRAwearingcourseremainsthepreferredwearingcourseontrunkroadsincludingmotorwaybut，since1999thinsurfacingshavebeenthepreferredoptioninEnglandandWales.Since1999inNorthernIreland,HRAwearingcourseandthinsurfacingsarethepreferredpermittedoptions.Porousasphalt(PA)isauniformlygradedmaterialwhichisdesignedtoprovide—4—中英文资料largeairvoidssothatwatercandraintothevergeswithinthelayerthickness.Ifthewearingcourseistobeeffective,thebasecoursebelowmustbewaterproofandthePAmusthavetheabilitytoretainitsopentexturedpropertieswithtime.Thickbinderfilmsarerequiredtoresistwaterdamageandageingofthebinder.Inuse,thismaterialminimizesvehiclespray,providesaquietrideandlowerrollingresistancetotrafficthandensemixtures.Itisoftenspecifiedforenvironmentalreasonsbutstonemasticasphalt(SMA)andspecialthinsurfacingsaregenerallyfavouredincurrentUKpractice.TherehavebeenhighprofileinstanceswhereaPAwearingcoursehasfailedearlyinitslife.TheHighwaysAgencydoesnotrecommendtheuseofaPAattrafficlevelsabove6000commercialvehiclesperday.Asphalticconcreteanddensebitumenmacadam(DBM)arecontinuouslygradedmixturessimilarinprincipletotheDBMsusedinroadbasesandbasecoursesbutwithsmallermaximumparticlesizes.AsphalticconcretetendstohaveaslightlydensergradingandisusedforroadsurfacesthroughouttheworldwiththeexceptingoftheUK.ItismoredifficulttomeetUKskidresistanceStandardswithDBMsthanHRA,SMAorPA.ThisproblemcanberesolvesbyprovidingaseparatesurfacetreatmentbutdoingsogenerallymakesDBMeconomicallyunattractive.Stonemasticasphalt(SMA)materialwaspioneeredinGermanyandScandinaviaandisnowwidelyusedintheUK.SMAhasacoarse,aggregrateskeleton,likePA,butthevoidsarefilledwithafineaggregate/filler/bitumenmortar.Inmixturesusingpenetrationgradebitumen,fibresareaddedtoholdthebitumenwithinthemixture(toprevent“binderdrainage”).Bitumenoilbitumen(earthoil)naturalbitumenTarWhereapolymermodifiedbitumenisused,thereisgenerallynoneedforfibres.SMAisagap-gradedmaterialwithgoodresistancetoruttingandhighdurability.modifiedbitumenSBSSBRItdiffersfromHRAinthatthemortarisdesignedtojustfillthevoidsinthecoarseaggregatewhereas,inHRA,coarseaggregateisintroducedintothemortaranddoesnotprovideacontinousstonematrix.ThehigherstonecontentHRAs,however,arerathersimilartoSMAbutarenotwideusedaswearingcoursesintheUK,beingpreferredforroadbaseandbasecourseconstruction.Avarietyofthinandwhatwerecalledultrathinsurfacings(nowadays,thetendencyistousetheterm„thinsurfacings‟forboththinandultrathinsurfacings)—5—中英文资料havebeenintroducedinrecentyears,principallyasaresultofdevelopmentworkconcentratedinFrance.ThesematerialsvaryintheirdetailedconstituentsbutusuallyhaveanaggregategradingsimilartoSMAandoftenincorporateapolymermodifiedbitumen.Theymaybeusedoverahighstiffnessroadbaseandbasecourseorusedforresurfacingofexistingpavements.Forheavydutypavements(i.ethosedesignedtohaveausefullifeoffortyyears),themaintenancephilosophyisoneofminimumlaneoccupancy,whichonlyallowstimeforreplacementofthewearingcoursetotheselonglifepavementstructures.Thenewgenerationrfainsallowsthistobeconvenientlyachieved.ThevariousgenericmixturetypesdescribedabovecanbecomparedwithrespecttotheirmechanicalpropertiesanddurabilitycharacteristicsbyreferencetoFig.12.1.Thisshows,inprinciple,howlowstonecontentHRA,asphalticconcrete,SMAandPAmixturesmobilizeresistancetoloadingbytraffic.Asphalticconcrete(Fig.12.1a))presentssomethingofacompromisewhenwelldesigned,sincethedenseaggregategradingcanoffergoodresistancetotheshearstresseswhichcauserutting,whileanadequatebindercontentwillprovidereasonableresistancetothetensilestresseswhichcausecracking.Ingeneral,theroleoftheaggregatedominates.DBMstendtohavelessdensegradingsandpropertieswhich,therefore,tendtowardsgoodruttingresistanceandawayfromgoodcrackresistance.HRA(Fig.12.1b))offersparticularlygoodresistancetocrackingthroughthebinderrichmortarbetweenthecoarseaggregateparticles.Thisalsoprovidesgooddurabilitybutthelackofcoarseaggregatecontentinhibitsresistancetorutting.SMAandPAareshowninthesamediagram(Fig.c))toemphasisthedominantrolethecoarseaggregate.Inbothcase,wellcoatedstoneisused.InPA,thevoidspaceremainsavailablefordrainageofwater,whilstinSMA,thespaceisoccupiedbyafineaggregate/filler/bitumen/fibremortar.Bothmaterialsoffergoodruttingresistancethroughthecoarseaggregatecontent.ThetensilestrengthofPAislowwhilstthatofSMAisprobablyadequatebutlittlemechanicaltestingdatahavebeenreportedtodate.—6—中英文资料DrainageforRoadandAirportsProvisionofadequatedrainageisimportantfactorinthelocationandgeometricdesignofroadandairports.Drainagefacilitiesonanyhighway,streetandairportshouldadequatelyprovidefortheflowofwaterawayfromthesurfaceofthepavementtoproperlydesignedchannels.Inadequatedrainagewilleventuallyresultinseriousdamagetothestructure.Inaddition,trafficmaybeslowedbyaccumulatedwateronthepavement,andaccidentsmayoccurasaresultofhydroplaningandlossofvisibilityfromsplashandspray.Theimportanceofadequatedrainageisrecognizedintheamountofhighwayconstructiondollarsallocatedtodrainagefacilities.About25percentofhighwayconstructiondollarsarespentforerosioncontrolanddrainagestructures,suchasculverts,bridges,channels,andditches.HighwayDrainageStructuresOneofthemainconcernsofthehighwayengineeristoprovideanadequatesizestructure,suchthatthewaterwayopeningissufficientlylargetodischargetheexpectedflowofwater.Inadequatelysizedstructurescanresultinwaterimpounding,whichmayleadtofailureoftheadjacentsectionsofthehighwayduetoembankmentsbeingsubmergedinwaterforlongperiods.Thetwogeneralcategoriesofdrainagestructuresaremajorandminor.Majorstructuresarethosewithclearspansgreaterthan20feet,whereasminorstructuresarethosewithclearspansof20feetorless.—7—中英文资料Majorstructuresareusuallylargebridges,althoughmultiple-spanculvertsmayalsobeincludedinthisclass.Minorstructuresincludesmallbridgesandculverts.Emphasisisplacedonselectingthespanandverticalclearancerequirementsformajorstructures.Thebridgedeckshouldbelocatedabovethehighwatermark.TheclearanceabovethehighwatermarkdependsonwhetherthewaterwayisnavigableIfthewaterwayisnavigable,theclearanceabovethehighwatermarkshouldallowthelargestshipusingthechanneltopassunderneaththebridgewithoutcollidingwiththebridgedeck.Theclearanceheight,type,andspacingofpiersalsodependontheprobabilityoficejamsandtheextenttowhichfloatinglogsanddebrisappearonthewaterwayduringhighwater.Anexaminationofthebanksoneithersideofthewaterwaywillindicatethelocationofthehighwatermark,sincethisisusuallyassociatedwithsignsoferosionanddebrisdeposits.Localresidents,whohavelivednearandobservedthewaterwayduringfloodstagesoveranumberofyears,canalsogivereliableinformationonthelocationofthehighwatermark.Streamgaugesthathavebeeninstalledinthewaterwayformanyyearscanalsoprovidedatathatcanbeusedtolocatethehighwatermark.Minorstructures,consistingofshort-spanbridgesandculverts,arethepredominanttypeofdrainagestructuresonhighways.Althoughopeningsforthesestructuresarenotdesignedtobeadequatefortheworstfloodconditions,theyshouldbelargeenoughtoaccommodatetheflowconditionsthatmightoccurduringthenormallifeexpectancyofthestructure.Provisionshouldalsobemadeforpreventingcloggingofthestructureduetofloatingdebrisandlargebouldersrollingfromthebanksofsteepchannels.Culvertsaremadeofdifferentmaterialsandindifferentshapes.Materialsusedtoconstructculvertsincludeconcrete（reinforcedandunreinforced）,corrugatedsteel,andcorrugatedaluminum.Othermaterialsmayalsobeusedtolinetheinterioroftheculverttopreventcorrosionandabrasionortoreducehydraulicresistance.Forexample,asphalticconcretemaybeusedtolinecorrugatedmetalculverts.Thedifferentshapesnormallyusedinculvertconstructionincludecircular,rectangular(box),elliptical,pipearch,metalbox,andarch.Thedrainageproblemisincreasedintheseareasprimarilyfortworeasons:theimperviousnatureoftheareacreatesaveryhighrunoff;andthereislittleroomfornaturalwatercourses.Itisoftennecessarytocollecttheentirestormwaterintoasystemofpipesandtransmititoverconsiderabledistancesbeforeitcanbeloosedagainassurfacerunoff.Thiscollectionandtransmissionfurtherincreasetheproblem,sinceallofthewatermustbecollectedwithvirtuallynopending,thuseliminatinganynaturalstorage;andthroughincreasedvelocitythepeakrunoffsarereachedmorequickly.Also,theshortertimesofpeakscausethesystemtobemoresensitivetoshort-duration,highintensiverainfall.Stormsewers,likeculvertsandbridges,aredesignedforstormsofvariousintensity-return-periodrelationships,dependingupon—8—中英文资料theeconomyandamountofpondingthatcanbetolerated.AirportDrainageTheproblemofprovidingproperdrainagefacilitiesforairportsissimilarinmanywaystothatofhighwaysandstreets.However,becauseofthelargeandrelativelyflatsurfaceinvolved,thevaryingsoilconditions,theabsenceofnaturalwatercoursesandpossiblesideditches,andthegreaterconcentrationofdischargeattheterminusoftheconstructionarea,somephasesoftheproblemaremorecomplex.Fortheaverageairporttheover-allareatobedrainedisrelativelylargeandanextensivedrainagesystemisrequired.Themagnitudeofsuchasystemmakesitevenmoreimperativethatsoundengineeringprinciplesbasedonallofthebestavailabledatabeusedtoensurethemosteconomicaldesign.Overdesigningoffacilitiesresultsinexcessivemoneyinvestmentwithnoreturn,andunderdesigningcanresultinconditionshazardoustotheairtrafficusingtheairport.Inordertoensuresurfacesthataresmooth,firm,stable,andreasonablyfreefromflooding,itisnecessarytoprovideasystemwhichwilldoseveralthings.Itmustcollectandremovethesurfacewaterfromtheairportsurfaces;