公路工程課件

Lesson27HIGHWAYENGINEERINGTransportationhasalwaysbeenoneofthemostimportantaspectsofcivilengineering.OneofthegreatestaccomplishmentsofRomanengineerswasthehighwaysystemthatmaderapidcommunicationpossiblebetweenRomeandtheprovincesoftheempire.Modernhighwaysarebuiltaccordingtotheprincipleslaiddownintheeighteenthandearlynineteenthcenturies.Generallyspeaking,alignment,subgrade,andpavementarethemostbasicthreepartsofthemodernhighways.交通一直是土木工程中最重要的方面之一。一位羅馬工程師的最偉大的成就是公路體系，其使快速通訊成為可能。現(xiàn)代公路的修建是根據(jù)十八和十九世紀初所定下的原則。一般而言，線性，路基，路面是現(xiàn)代公路的最基本的三個部分。

Introductionaccomplishment成就alignment線性subgrade路基pavemen路面Thealignmentofaroadincludeshorizontalalignmentandverticalalignment.Thehorizontalalignmentofaroadisshownontheplanviewandisaseriesofstraightlinescalledtangentsconnectedbycircularcurves.Inmodernpracticeitiscommontointerposetransitionorspiralcurvesbetweentangentsandcircularcurves.Sotheelementsofthehorizontalalignmentaretangent,circularcurve,andtransitioncurve,asshowninfollowingFig.27-1.公路線形包括平面線形和縱斷面線形。道路的平面線形顯示在平面圖和一系列的直線稱為圓曲線連接切線。目前在實際操作中，一般在切線和圓曲線之間插入緩和曲線或螺旋曲線。平面線形的組成是切線（直），圓曲線和過渡曲線，如圖中下面的圖27-1。1.Alignment（線形）horizontalalignment平面線形verticalalignment縱斷面線形tangent切線circularcurve圓曲線CurvelineStraightlineTheverticalalignmentofaroadisshownonthecutawayview.Theelementsoftheverticalalignmentaretangents,verticalcurves.Usuallytherearetwotypeofverticalcurve:convexverticalcurveandconcaveverticalcurve,asshowninfollowingFig.27-2.道路的縱斷面線形顯示在剖視圖?？v斷面線形的組成是切線，豎曲線。通常有兩種類型的豎曲線：垂直凸豎曲線和凹豎曲線，如圖以下所示27-2。cutaway剖面convex凸的concave凹的Long,flatcurvesarepreferableatalltimes,astheyarepleasinginappearanceanddecreasepossibilityoffutureobsolescence.Long,flatcurvesshouldbeusedforsmallchangesindirection,asshortcurvesappearas'kink'.Alsohorizontalandverticalalignmentmustbeconsideredtogether,notseparately.Forexample,asharphorizontalcurvebeginningnearacrestcancreateaseriousaccidenthazard.在任何時候都長且平坦的曲線都是優(yōu)選，因為它們在外觀上令人愉悅并能減少將來報廢的可能性。長，平面曲線應該用于在方向上的微小變化，如短的曲線顯示為“扭結”。同時平面線形和縱斷面線形必須一起考慮，而不是分開。例如，一個銳的平曲線的開始接近高峰時可能會產(chǎn)生嚴重事故的危險。obsolescence報廢crest高峰Avehicletravelinginacurvedpathissubjecttocentrifugalforce.Thisisbalancedbyanequalandoppositeforcedevelopedthroughsuperelevationandsidefriction.Fromahighwaydesignstandpoint,bothsuperelevationandsidefrictioncannotexceedcertainmaximums,andthesecontrolsplacelimitsonthesharpnessofcurvesthatcanbeusedwithadesignspeed.車輛在彎曲道路行駛受到離心力。這個平衡通過大小相等方向相反的超高和側(cè)向摩擦力來達到。從公路設計的觀點來講，超高和側(cè)向摩擦力都不能超過某個最大值，這些控制值設置了曲線銳度限值，曲線銳度限值可以與設計速度建立聯(lián)系。vehicle車輛centrifugalforce離心力superelevation超高sidefriction側(cè)向摩擦力Whenroadsintersectorarailroadspansacrossaroad,theroadintersectionsareneeded.Theintersectioncanbeat-gradeintersectionandgrade-separatedjunction.Thefreewaysonlyadoptthelatterintersection.Thetypicalat-gradecrossingsarecrossroads,Tintersection,androtaryintersection,asshowninfollowingFig.27-3.當相交的道路或鐵路橫跨道路時，需要設置道路交叉口。交叉口可以是平面交叉的和立體交叉。該高速公路僅采用后者的交叉口。典型的平面交叉口的十字路口，T形交叉，及環(huán)形交叉，如圖下所示27-3。intersect交叉junction連接rotary環(huán)形高速公路普通公路與高速公路的轉(zhuǎn)彎線形的比較Whenroadsintersectorarailroadspansacrossaroad,theroadintersectionsareneeded.Theintersectioncanbeat-gradeintersectionandgrade-separatedjunction.Thefreewaysonlyadoptthelatterintersection.Thetypicalat-gradecrossingsarecrossroads,Tintersection,androtaryintersection,asshowninfollowingFig.27-3.當相交的道路或鐵路橫跨道路時，需要設置道路交叉口。交叉口可以是平面交叉的和立體交叉。該高速公路僅采用后者的交叉口。典型的平面交叉口的十字路口，T形交叉，及環(huán)形交叉，如圖下所示27-3。intersect交叉junction連接rotary環(huán)形Thefoundationsunderpavementofhighwaysaresubgrade,sohighwaysubgrade(orbasementsoil)maybedefinedasthesupportingstructureonwhichpavementanditsspecialundercoursesrest.Thepurposeofapavementistoprovideasmoothsurfaceoverwhichvehiclesmaypassunderallclimateconditions.Becausenaturalterrainsareuneven,togetsmoothroad,cuttingandfillingareneededtochangethenaturalterrain.Subgradesareclassifiedintoembankment,cutting,andpart-cutpart-fillsubgrade,。作業(yè)：將下段英文翻譯成漢語。Incutsections,thesubgradeistheoriginalsoillyingbelowthespeciallayersdesignatedasbaseandsubbasematerial.Infillsections,thesubgradeisconstructedoverthenativegroundandconsistsofimportedmaterialfromnearbyroadwaycutsorfromborrowpits.在挖方部分，路基是置于被設計為基座和底基層特殊層下方的天然土。在填方部分，路基建造于原土之上并由附近公路挖方或從取土坑中的土這類外來材料組成。Theperformanceofthepavementisaffectedbythecharacteristicsofthesubgrade.Desirablepropertiesthatthesubgradeshouldpossessincludestrength,drainage,easeofcompaction,permanencyofcompaction,andpermanencyofstrength.在路面的性能受路基特性的影響。路基的理想性能，應具有包括強度，排水，易壓實性，壓實的永久性和強度的永久性。drainage排水possess控制，具有Soilsengineersagreethatthepropertiesofasoilmixtureareinfluencedmorebymoisturethanbyanyothercause.Soilsthathaveamplestrengthandsupportingpowerunderonesetofmoistureconditionsmaybeentirelyunsatisfacoryifthepercentageofmoisturechanges.Onedifficultywithsoilsinhighwaysubgradesisthattheyaresubjecttosuchmoisturechanges.土力學工程師贊同濕度對土壤混合物性能的影響比其他因素大。在一個濕度條件下有足夠強度與支撐能力的土體，如果濕度的百分比發(fā)生變化，土體可能完全不能令人滿意。土體在公路路基中的一個困難是承受著濕度的變化。mixture混合物moisture濕度percentage

百分比Soilisahighlyvariablematerial;theinterrelationshipofsoiltexture,density,moisturecontent,andstrengtharecomplex,andbehaviorunderrepeatedloadsisdifficulttoevaluate.Becauseofthecomplexityoftheproblem,itisnotpossibletosetdownrulesthatwillbesuitableforallcase.

土壤是高度多變的材料；土壤的結構、密度、含水率及強度的內(nèi)在關系是非常復雜的，在荷載重復作用下的狀態(tài)是很難估計的。由于問題的復雜性，不可能制定適用于所有狀況的規(guī)則.interrelationship內(nèi)在關系texture結構density密度evaluate估計

Forexample,thesupportingpowerofsoilsincreaseswithdensity.Aroadconstructedonagivensoilmaybeentirelysatisfactoryifthesoilisproperlycompacted.Ontheotherhand,theroadmayfailifthesoilisinsufficientlycompacted,particularlyifthevoidsbecomefilledwithwater.

例如，隨著密度的提高，土壤的支撐力增強。路修建在被適當壓實的給定土體上那會是完全令人滿意的。另一方面，如果土沒有被充分壓縮，特別是如果土體的孔隙充滿了水，道路可能會失效。TranslatethefollowingsentencesintoChinese.highwayalignmentExercisesclover-leafinterchangecentrifugalforcecutawayviewmoisturetransitioncurveplanview4.苜蓿葉立體交叉5.緩和曲線8.離心力2.公路線形6.平面圖3.路基1.濕度subgrade7.剖面圖1.Inmodernpracticeitiscommontointerposetransitionorspiralcurvesbetweentangentsandcircularcurves.2.必須避免平地突然變化為急彎以及很長的切線后緊跟著銳曲線，否則就會產(chǎn)生事故風險。2.Suddenchangesfromflattosharpcurvesandlongtangentsfollowedbysharpcurvesmustbeavoided;otherwise,accidenthazardswillbecreated.1.目前在實際操作中，一般在切線和圓曲線之間插入緩和曲線和螺旋曲線。3.因為自然地形是不平坦的，為了得到平坦的道路，需要挖方和填方來改變自然地形。3.Becausenaturalterrainsareuneven,togetsmoothroad,cuttingandfillingareneededtochangethenaturalterrain.4.Soilsthathaveamplestrengthandsupportingpowerunderonesetofmoistureconditionsmaybeentirelyunsatisfacoryifthepercentageofmoisturechanges.5.另一方面，如果土沒有被充分壓縮，特別是如果土體的孔隙充滿了水，道路可能會失效。5.Ontheotherhand,theroadmayfailifthesoilisinsufficientlycompacted,particularlyifthevoidsbecomefil