交通工程专业外文翻译外文文献英文文献

2012土木工程学院交通工程专业中英文翻译RoadDesign专业：交通工程2012英文原文TheBasicsofaGoodRoadWehaveknownhowtobuildgoodroadsforalongtime.ArchaeologistshavefoundancientEgyptianroadsthatcarriedblockstothepyramidsin4600BCE.Later,theRomansbuiltanextensiveroadsystem,usingthesameprinciplesweusetoday.Someoftheseroadsarestillinservice.Ifyoufollowthebasicconceptsofroadbuilding,youwillcreatearoadthatwilllast.Thetencommandmentsofagoodroadare:（1）Getwaterawayfromtheroad（2）Buildonafirmfoundation（3）Usethebestmaterials（4）Compactalllayersproperly（5）Designfortrafficloadsandvolumes（6）Designformaintenance（7）Paveonlywhenready（8）Buildfromthebottomup（9）Protectyourinvestment（10）Keepgoodrecords1．GetwaterawayfromtheroadWecan’toveremphasizetheimportanceofgooddrainage.Engineersestimatethatatleast90%ofaroad’sproblemscanberelatedtoexcesswaterortopoorwaterdrainage.Toomuchwaterinanylayerofaroad’sstructurecanweakenthatlayer,leadingtofailure.Inthesurfacelayer,watercancausecracksandpotholes.Inlowerlayersitunderminessupport,causingcracksandpotholes.Acommonsignofwaterinanasphaltroadsurfaceisalligatorcracking—aninterconnectedpatternofcracksformingsmallirregularshapedpiecesthatlooklikealligatorskin.Edgecracking,frostheaves,andspringbreakupofpavementsalsopointtomoistureproblems.Topreventtheseproblemsrememberthatwater:•flowsdownhill•needstoflowsomeplace•isaproblemifitisnotflowingEffectivedrainagesystemsdivert,drainanddisposeofwater.Todothistheyuseinterceptorditchesandslopes,roadcrowns,andditchandculvertsystems.Divert—Interceptorditches,locatedbetweentheroadandhighergroundalongtheroad,keepthewaterfromreachingtheroadway.Theseditchesmustslopesotheycarrywaterawayfromtheroad.Drain—Creatingacrownintheroadsoitishigheralongthecenterlinethanattheedgesencourageswatertoflowofftheroad.Typicallyapavedcrownshouldbe1⁄4higherthantheshoulderforeachfootofwidthfromthecenterlinetotheedge.Forgravelsurfacesthecrownshouldbe1⁄2higherperfootofwidth.Forthisflowpathtowork,theroadsurfacemustberelatively2012watertight.Roadshouldersalsomustbeslopedawayfromtheroadtocontinuecarryingtheflowaway.Superelevations(banking)attheoutsideofcurveswillalsohelpdraintheroadsurface.Dispose—Aditchandculvertsystemcarrieswaterawayfromtheroadstructure.Ditchesshouldbeatleastonefootlowerthanthebottomofthegravelroadlayerthatdrainstheroadway.Theymustbekeptcleanandmustbeslopedtomovewaterintonaturaldrainage.Ifwaterstaysintheditchesitcanseepbackintotheroadstructureandundermineitsstrength.Ditchesshouldalsobeprotectedfromerosionbyplantinggrass,orinstallingrockandothererosioncontrolmeasures.Erosioncandamageshouldersandditches,clogculverts,undermineroadbeds,andcontaminatenearbystreamsandlakes.Evaluateyourditchandculvertsystemtwiceayeartoensurethatitworks.Inthefall,cleanoutleavesandbranchesthatcanblockflow.Inspring,checkforandremovesiltsfromplowingandanydeadplantmaterialleftfromthefall.2．BuildonafirmfoundationAroadisonlyasgoodasitsfoundation.Ahighwaywearsoutfromthetopdownbutfallsapartfromthebottom.Theroadbasemustcarrytheentirestructureandthetrafficthatusesit.Tomakeafirmfoundationyoumayneedtostabilizetheroadbedwithchemicalstabilizers,largestonecalledbreakerrun,orgeotextilefabric.Whenyourunintoconditionswhereyoususpectthatthenativesoilisunstable,workwithanengineertoinvestigatethesituationanddesignanappropriatesolution.3．UsethebestmaterialsWithallroadmaterialsyou“paynoworpaylater.”Inferiormaterialsmayrequireextensivemaintenancethroughouttheroad’slife.Theymayalsoforceyoutoreplacetheroadprematurely.Crushedaggregateisthebestmaterialforthebasecourse.Thesharpanglesofthecrushedmaterialinterlockwhentheyarecompacted.Thissupportsthepavementandtrafficbytransmittingtheloadfromparticletoparticle.Bycontrast,roundedparticlesactlikeballbearings,movingunderloads.Angularparticlesaremorestablethanroundedparticles.Asphaltandconcretepavementmaterialsmustbeofthehighestquality,designedfortheconditions,obtainedfromestablishedfirms,andtestedtoensureitmeetsspecifications.4．CompactalllayersIngeneral,themoredenselyamaterialiscompacted,thestrongeritis.Compactionalsoshrinksoreliminatesopenspaces(voids)betweenparticles.Thismeansthatlesswatercanenterthestructure.Waterinsoilcanweakenthestructureorleadtofrostheaves.Thisisespeciallyimportantforunsurfaced(gravel)roads.Usegravelwhichhasamixofsizes(well-gradedaggregate)sosmallerparticlescanfillthevoidsbetweenlargerones.Goodcompactionofasphaltpavementlengthensitslife.5．DesignfortrafficloadsandvolumesDesignforthehighestanticipatedloadtheroadwillcarry.Aroadthathasbeendesignedonlyforcarswillnotstanduptotrucks.Onetruckwith9tonsonasinglerearaxledoesasmuchdamagetoaroadasnearly10,000cars.Ruralroadsmaycarrylogtrucks,milktrucks,firedepartmentpumpertrucks,orconstructionequipment.Ifyoudon’tknowwhatspecificloadstheroadwillcarry,agoodruleofthumbistodesignforthelargestpieceofhighwaymaintenanceequipmentthatwillbeusedontheroad.Awell-constructedandmaintainedasphaltroadshouldlast20yearswithoutmajorrepairsor2012reconstruction.Indesigningaroad,usetrafficcountsthatprojectnumbersandsizesofvehicles20yearsintothefuture.Theseareonlyprojections,atbest