道路路面畢業(yè)設計外文翻譯

1、<p>　　畢業(yè)論文（外文翻譯）</p><p><b>　?。?012屆）</b></p><p>　　學院名稱 土木與水利工程學院 </p><p>　　專 業(yè) （班 級） 土木工程七班 </p><p>　　姓 名 （學 號）

2、 李 小 潤（20083650） </p><p>　　指 導 教 師 扈 惠 敏 </p><p>　　系（教研室）負責人 方 詩 圣 </p>

3、<p><b>　　Pavement</b></p><p>　　Highway pavements are divided into two main categories: rigitand flexible. </p><p>　　The wearing surfaceof a rigid pavement is usually constructe

4、d of Portland cement concrete such that it acts like a beam over any irregularities in the underlying supporting material. </p><p>　　The wearing surface of flexible pavements, on the other hand, is usually c

5、onstructed of bituminous material such that they remain in contact with the underlying material even when minor irregularities occur.</p><p>　　Flexible pavements usually consist of a bituminous surface under

6、laid with a layer of granular material and a layer of a suitable mixture of coarse and fine materials. </p><p>　　Coarse aggregates </p><p>　　Fine aggregates</p><p>　　Traffic loads a

7、re transferred by the wearing surface to the underlying supporting materials through the interlocking of aggregates, the frictionaleffect of the granular materials, and the cohesion of the fine materials.</p><

8、p>　　Flexible pavements are further divided into three subgroups: high type, intermediate type, and low type. High-type pavements have wearing surfaces that adequately support the expected traffic load without visible

9、distress due to fatigue and are not susceptible to weather conditions. </p><p>　　Intermediate-type pavements have wearing surfaces that range from surface treated to those with qualities just below that of h

10、igh-type pavements. Low-type pavements are used mainly for low-cost roads and have wearing surfaces that range from untreated to loose natural materials to surface-treated earth.</p><p>　　The components of a

11、 flexible pavement include the subgradeor prepared roadbed, the subbase, basecourse, and the surface course (Fig.11.1). </p><p>　　Upper surface course</p><p>　　Middle surface course </p>

12、<p>　　Lower surface course </p><p>　　The performance of the pavement depends on the satisfactory performance of each component, which requires proper evaluation of the properties of each component separ

13、ately.</p><p>　　The subgrade is usually the natural material located along the horizontal alignment of the pavement and serves as the foundation of the pavement structure. </p><p>　　The subgrad

14、emay also consist of a layer of selected borrow materials, well compacted to prescribedspecifications.</p><p>　　Compacting plant </p><p>　　Compaction device </p><p>　　Compactness

15、 </p><p>　　It may be necessary to treat the subgrade material to achieve certain strength properties required for the type of pavement being constructed.</p><p>　　Located immediately above the s

16、ubgrade, the subbase component consists of a superior quality to that which generally is used for subgrade construction. The requirements for subbase materials are usually given in terms of the gradation, plastic charact

17、eristics, and strength. When the quality of the subgrade material meets the requirements of the subbase material, the subbase component may be omitted. </p><p>　　In cases where suitable subbase material

18、is not readily available ,the available material can be treated with other materials to achieve the necessary properties. This process of treating soils to improve their engineering properties is know as stabilization.&l

19、t;/p><p>　　The base course lies immediately above the subbase. It is placed immediately above the subgrade if a subbase course is not used.</p><p>　　This course usually consists of granular materia

20、ls such as crushed stone, crushed or uncrushed. </p><p>　　The specifications for base course materials usually include stricter requirements than those for subbase materials, particularly with respect to the

21、ir plasticity, gradation, and strength. </p><p>　　Materials that do not have the required properties can be used as base materials if they are properly stabilized with Portland cement, asphalt, or lime .<

22、/p><p>　　In some cases, high-quality base course materials may also be treated with asphalt or Portland cement to improve the stiffness characteristics of heavy-duty pavementsThe surface course is the upper cou

23、rse of the road pavement and is constructed immediately above the base course. The surface course in flexible pavement usually consists of a mixture of mineral aggregates and asphaltic materials. </p><p>　　I

24、t should be capable of withstanding high tire pressures, resisting the abrasive forces due to traffic, providing a skid-resistant driving surface, and preventing the penetration of surface water into the underlying layer

25、s. </p><p>　　The thickness of the wearing surface can vary from 3 in. to more than 6 in.（inch，英寸，2.54cm） , depending on the expected traffic on the pavement. It was shown that the quality of the surface cour

26、se of a flexible pavement depends on the mix design of the asphalt concrete used.</p><p>　　Rigid highway pavements usually are constructed to carry heavy traffic loads, although they have been used for resid

27、ential and local roads. Properly designed and constructed rigid pavements have long service lives and usually are less expensive to maintain than the flexible pavements.</p><p>　　The Portland cement concrete

28、 commonly used for rigid pavements consists of Portland cement, coarse aggregate, fine aggregate, and water. Steel reinforcing rods may or may not be used, depending on the type of pavement being constructed.</p>

29、<p>　　Rigid highway pavements be divided into three general type: plain concrete pavements, simply reinforced concrete pavements, and continuously reinforced concrete pavement. The definition of each pavement type

30、is related to the amount of reinforcement used.</p><p>　　Plain concrete pavement has no temperature steel or dowels for load transfer. However, steel tie bars are often used to provide a hingeeffect at longi

31、tudinal joints and to prevent the opening of these joints. Plain concrete pavements are used mainly on low-volume highways or when cement-stabilized soils are used as subbase. </p><p>　　Joints are placed at

32、relatively shorter distances (10 to 20 ft) than with the other</p><p>　　types of concrete pavements to reduce the amount of cracking. </p><p>　　In some case, the transverse joints of plain concr

33、ete pavements are skewed about 4 to 5 ft in plan, such that only one wheel of a vehicle passes through the joint at a time. This helps to provide a smoother ride.</p><p>　　Simply reinforced concrete pavemen

34、ts have dowels for the transfer of traffic loads across joints, with these joints spaced at larger distances, ranging from 30 to 100 ft. Temperature steel is used throughout the slab, with the amount dependent on the len

35、gth of the slab. Tie bars are also commonly used in longitudinal joints.</p><p>　　Continuously reinforced concrete pavements have no transverse joints, except construction joints or expansion joints when the

36、y are necessary at specific positions, such as at bridges. </p><p>　　These pavements have a relatively high percentage of steel, with the minimum usually at 0.6 percent of the cross section of the slab. They

37、 also contain tie bars across the longitudinal joints.</p><p>　　Bituminous Surface Courses</p><p>　　The bituminous surface course has to provide resistance to the effects of repeated loading by

38、tyres and to the effects of the environment. </p><p>　　In addition, it must offer adequate skid resistance in wet weather as well as comfortable vehicle ride. It must also be resistant to rutting and to crac

39、king. </p><p>　　It is also desirable that surface course is impermeable, except in the case of porous asphalt.</p><p>　　Hot rolled asphalt (HRA) is a gapgraded material with less coarse aggregat

40、e. In fact it is essentially a bitumen/fine aggregate/filler mortar into which some coarse aggregate is placed. </p><p>　　The mechanical propertiesare dominated by those of the mortar. This material has been

41、 extensively used as the wearing course on major road in the UK, though its use has recently declined as new materials have been introduced. </p><p>　　It provides a durablelayer with good resistance to crack

42、ing and one which is relatively easy to compact. The coarse aggregate content is low (typically 30%) which results in the compacted mixture having a smooth surface. Accordingly, the skid resistance is inadequate and prec

43、oated chippings are rolled into the surface at the time of laying to correct this deficiency.</p><p>　　In Scotland, HRA wearing course remains the preferred wearing course on trunk roads including motorway b

44、ut， since 1999 thin surfacings have been the preferred option in England and Wales. Since 1999 in Northern Ireland, HRA wearing course and thin surfacings are the preferred permitted options. </p><p>　　Porou

45、s asphalt (PA) is a uniformly graded material which is designed to provide large air voids so that water can drain to the verges within the layer thickness. If the wearing course is to be effective, the basecourse below

46、must be waterproof and the PA must have the ability to retain its open textured properties with time. </p><p>　　Thick binder films are required to resist water damage and ageing of the binder. In use, this m

47、aterial minimizes vehicle spray, provides a quiet ride and lower rolling resistance to traffic than dense mixtures. </p><p>　　It is often specified for environmental reasons but stone mastic asphalt (SMA) an

48、d special thin surfacings are generally favoured in current UK practice. There have been high profile instances where a PA wearing course has failed early in its life. The Highways Agency does not recommend the use of a

49、PA at traffic levels above 6000 commercial vehicles per day.</p><p>　　Asphaltic concrete and dense bitumen macadam (DBM) are continuously graded mixtures similar in principle to the DBMs used in roadbases an

50、d basecourses but with smaller maximum particle sizes. Asphaltic concrete tends to have a slightlydenser grading and is used for road surfaces throughout the world with the excepting of the UK. </p><p>　　It

51、is more difficult to meet UK skid resistance Standards with DBMs than HRA, SMA or PA. This problem can be resolves by providing a separate surface treatment but doing so generally makes DBM economically unattractive.<

52、;/p><p>　　Stone mastic asphalt (SMA) material was pioneeredin Germany and Scandinavia and is now widely used in the UK. SMA has a coarse, aggregrate skeleton, like PA, but the voids are filled with a fine aggre

53、gate/filler /bitumen mortar. </p><p>　　In mixtures using penetration grade bitumen , fibres are added to hold the bitumen within the mixture (to prevent “binder drainage”). </p><p>　　Bitumen

54、 </p><p>　　oil bitumen( earth oil)</p><p>　　natural bitumen</p><p><b>　　Tar </b></p><p>　　Where a polymer modified bitumen is used, there is generally no n

55、eed for fibres. SMA is a gap-graded material with good resistance to rutting and high durability. </p><p>　　modified bitumen </p><p><b>　　SBS</b></p><p><b>　　SBR&l

56、t;/b></p><p><b>　　PE\EVA</b></p><p>　　It differs from HRA in that the mortar is designed to just fill the voids in the coarse aggregate whereas, in HRA, coarse aggregate is introd

57、uced into the mortar and does not provide a continous stone matrix. The higher stone content HRAs ,however, are rather similar to SMA but are not wide used as wearing courses in the UK, being preferred for roadbase and b

58、asecourse construction. </p><p>　　A variety of thin and what were called ultra thin surfacings (nowadays, the tendency is to use the term ‘thin surfacings’ for both thin and ultra thin surfacings ) have been

59、 introduced in recent years, principally as a result of development work concentrated in France. </p><p>　　These materials vary in their detailed constituents but usually have an aggregate grading similar to

60、 SMA and often incorporate a polymer modified bitumen. </p><p>　　They may be used over a high stiffness roadbase and basecourse or used for resurfacing of existing pavements. For heavy duty pavements (i .e t

61、hose designed to have a useful life of forty years), the maintenance philosophy is one of minimum lane occupancy, which only allows time for replacement of the wearing course to these ‘long life’ pavement structures. The

62、 new generation of thin surfacings allows this to be conveniently achieved. </p><p>　　The various generic mixture types described above can be compared with respect to their mechanical properties and durabil

63、ity characteristics by reference to Fig.12.1. This shows, in principle, how low stone content HRA, asphaltic concrete, SMA and PA mixtures mobilize resistance to loading by traffic.</p><p>　　Asphaltic concre

64、te (Fig.12.1a)) presents something of a compromise when well designed, since the dense aggregate grading can offer good resistance to the shear stresses which cause rutting, while an adequate binder content will provide

65、reasonable resistance to the tensile stresses which cause cracking. </p><p>　　In general, the role of the aggregate dominates. DBMs tend to have less dense gradings and properties which, therefore, tend towa

66、rds good rutting resistance and away from good crack resistance.</p><p>　　HRA (Fig.12.1b)) offers particularly good resistance to cracking through the binder rich mortar between the coarse aggregate particle

67、s. This also provides good durability but the lack of coarse aggregate content inhibits resistance to rutting.</p><p>　　SMA and PA are shown in the same diagram ( Fig.c)) to emphasis the dominant role the co

68、arse aggregate. In both case, well coated stone is used. In PA, the void space remains available for drainage of water, whilst in SMA, the space is occupied by a fine aggregate/ filler/ bitumen/ fibre mortar. </p>

69、<p>　　Both materials offer good rutting resistance through the coarse aggregate content. The tensile strength of PA is low whilst that of SMA is probably adequate but little mechanical testing data have been report

70、ed to date.</p><p>　　Drainage for Road and Airports</p><p>　　Provision of adequate drainage is important factor in the location and geometric design of road and airports. Drainage facilities o

71、n any highway, street and airport should adequately provide for the flow of water away from the surface of the pavement to properly designed channels. </p><p>　　Inadequate drainage will eventually result in

72、 serious damage to the structure. </p><p>　　In addition, traffic may be slowed by accumulated water on the pavement, and accidents may occur as a result of hydroplaning and loss of visibility from splash and

73、 spray. The importance of adequate drainage is recognized in the amount of highway construction dollars allocated to drainage facilities. About 25 percent of highway construction dollars are spent for erosion control and

74、 drainage structures, such as culverts, bridges, channels, and ditches. </p><p>　　Highway Drainage Structures</p><p>　　One of the main concerns of the highway engineer is to provide an adequate

75、size structure, such that the waterway opening is sufficiently large to discharge the expected flow of water. </p><p>　　Inadequately sized structures can result in water impounding, which may lead to failure

76、 of the adjacent sections of the highway due to embankments being submerged in water for long periods.</p><p>　　The two general categories of drainage structures are major and minor. Major structures are tho

77、se with clear spans greater than 20 feet, whereas minor structures are those with clear spans of 20 feet or less . </p><p>　　Major structures are usually large bridges, although multiple-span culverts may al

78、so be included in this class. Minor structures include small bridges and culverts.</p><p>　　Emphasis is placed on selecting the span and vertical clearancerequirements for major structures. The bridge deck s

79、hould be located above the high water mark .The clearance above the high water mark depends on whether the waterway is navigable</p><p>　　If the waterway is navigable, the clearance above the high water mark

80、 should allow the largest ship using the channel to pass underneath the bridge without colliding with the bridge deck. The clearance height, type, and spacing of piers also depend on the probability of ice jams and the e

81、xtentto which floating logs and debris appear on the waterway during high water.</p><p>　　An examination of the banks on either side of the waterway will indicate the location of the high water mark, since t

82、his is usually associated with signs of erosion and debris deposits. Local residents, who have lived near and observed the waterway during flood stages over a number of years, can also give reliable information on the lo

83、cation of the high water mark. Stream gauges that have been installed in the waterway for many years can also provide data that can be used to locate the high wate</p><p>　　Minor structures, consisting of sh

84、ort-span bridges and culverts, are the predominant type of drainage structures on highways. Although openings for these structures are not designed to be adequate for the worst flood conditions, they should be large eno

85、ugh to accommodate the flow conditions that might occur during the normal life expectancy of the structure. </p><p>　　Provision should also be made for preventing clogging of the structure due to floating de

86、bris and large boulders rolling from the banks of steep channels.</p><p>　　Culverts are made of different materials and in different shapes. Materials used to construct culverts include concrete（ reinforced

87、and unreinforced）, corrugated steel, and corrugatedaluminum. Other materials may also be used to line the interiorof the culvert to prevent corrosion and abrasionor to reduce hydraulic resistance. For example, asphaltic

88、concrete may be used to line corrugated metal culverts. The different shapes normally used in culvert construction include circular, rectangular (b</p><p>　　The drainage problem is increased in these areas

89、primarily for two reasons: the impervious nature of the area creates a very high runoff; and there is little room for natural water courses. It is often necessary to collect the entire storm water into a system of pipes

90、and transmit it over considerable distances before it can be loosed again as surface runoff. This collection and transmission further increase the problem, since all of the water must be collected with virtually no pendi

91、ng, thus el</p><p>　　Also, the shorter times of peaks cause the system to be more sensitive to short-duration,high intensive rainfall.Storm sewers,like culverts and bridges,are designed for storms of various

92、 intensity-return-period relationships, depending upon the economy and amount of ponding that can be tolerated. </p><p>　　Airport Drainage </p><p>　　The problem of providing proper drainage faci

93、lities for airports is similar in many ways to that of highways and streets. However, because of the large and relatively flat surface involved, the varying soil conditions, the absence of natural water courses and possi

94、ble side ditches, and the greater concentration of discharge at the terminus of the construction area, some phases of the problem are more complex. For the average airport the over-all area to be drained is relatively la

95、rge and an exte</p><p>　　Overdesigning of facilities results in excessive money investment with no return, and underdesigning can result in conditions hazardous to the air traffic using the airport. In order

96、 to ensure surfaces that are smooth, firm, stable, and reasonably free from flooding, it is necessary to provide a system which will do several things.It must collect and remove the surface water from the airport surface

97、s; intercept and remove surface water flowing toward the airport from adjacent areas; collect and </p><p><b>　　路面</b></p><p>　　公路的路面被分為兩類：剛性的和柔性的。剛性路面的磨耗層通常用水泥混凝土鋪筑，其作用像梁一樣，放在不平整的下承層

98、上。另一方面，柔性路面的磨耗層通常用瀝青材料鋪筑，即使在有小的不平整出現(xiàn)的情況下，它們也可以保持和下層材料的接觸。柔性路面通常由兩層組成，一層為下?lián)斡幸粚恿Ａ喜牧系臑r青層；另一層為粗細集料適當混合的混合層。磨耗層通過集料間的嵌鎖力、粒料間的摩擦力以及細集料的粘聚力，將車輛荷載傳遞給下承層材料。</p><p>　　柔性路面進一步分為三個子群：高級、中級和低級。高級路面有磨耗層，足以承受預期的交通荷載，而不會出現(xiàn)明

99、顯的疲勞破壞，并且不易受氣候的影響。中級路面的磨耗層可以介于高級路面磨耗層與簡單路面處理之間。低級路面主要應用于低成本路面，其表面是從未處理的松散的天然材料到處理過的表面泥土。</p><p>　　柔性路面的組成部分包括地基、建筑好的路基、底基層、基層和面層。面層又分為：上面層、中面層、下面層。</p><p>　　道路的性能取決于每個成分的良好性能，它要求分別對每個組件的性能適當?shù)脑u價。

100、</p><p>　　路基通常是道路沿線的天然材料，它是路面結(jié)構的基礎。路基也可以由一層按規(guī)定標準壓實的借用材料選擇組成。根據(jù)修建路面類型的需要，有時對路基材料進行處理以達到一定的力學性能是很必要的。位于路基上，底基層組件通常由被用于路基工程的那種優(yōu)秀的組件構成。底基層材料的要求通常依照級配、塑性和強度。當路基材料的質(zhì)量達到底基層材料的要求時，底基層這一組件就會被省略。如果無法輕易得到合適的底基層材料，也可以將現(xiàn)

101、有材料與其他材料加工以達到必要的性能。這個改善土壤的過程是為了提高工程性質(zhì)，就像我們已經(jīng)知道的穩(wěn)固處理一樣?；鶎游挥诘谆鶎又?。如果不使用底基層則位于路基之上?；鶎邮怯闪Ａ喜牧媳热绫粔核檫^的或者解壓過的碎石。基層材料關于其塑性、級配和強度的特性的標準通常比底基層的材料要求更嚴格。當材料性能不符合要求時，如果使用水泥、瀝青或石灰進行適當?shù)募庸烫幚砗?，也可以用于基層。有時侯，質(zhì)量好的基層材料也需要用瀝青或水泥進行穩(wěn)定，以提高重交通路面的剛度