外文翻译--公路和机场路面设计

1、外文翻译一公路和机场路面设 计中文2942字本科生毕业设计（论文）外文资料翻译翻译资料名称（外文）:Highway and Airport Pavement Design翻译资料名称（中文）:公路和机场路面设计学 院： 建筑工程学院系专 业：土木工程（道桥）班 级：学 号：姓 名：指导教师：完成日期:2012 年0 2月 20 日2Highway and Airport Pavement Design (Excerpt)T. F. FvvaNational University of Singapore1. IntroductionPavements are designed and cons

2、tructed to provide durable all-weather traveling surfaces for safe and speedy movement of people and goods with an acceptable level of comfort to users. These functional requirements of pavements are achieved through careful considerations in the following aspects during the design and construction

3、phases: (a) selection of pavement type, (b) selection of materials to be used for various pavement layers and treatment of subgrade soils, (c) structural thickness design for pavement layers, (d) subsurface drainage design for the pavement system, (e) surface drainage and geometric design, and (f) r

4、idability of pavement surface.The two major considerations in the structural design of highway and airport pavements are material design and thickness design. Material design deals with the selection of suitable materials for various pavement layers and mix design of bituminous materials (for flexib

5、le pavement) or portland cement concrete (for rigid and interlocking block pavements). These topics are discussed in other chapters of this handbook. This chapter presents the concepts and methods of pavement thickness design. As the name implies，thickness design refers to the procedure of deterinin

6、ing the required thickness for each pavement layer to provide a structurally sound pavement structure with satisfactory performance for the design traffic over the selected design life. Drainage design examines the entire pavement structure with respect to its drainage requirements and incorporates

7、facilities to satisfy those requirements.2. Pavement Types and Materials2.1 Flexible versus Rigid PavementTraditionally, pavements are classified into two categories, namely flexible and rigid pavements. The basis for classification is the way by which traffic loads are transmitted to the subgrade s

8、oil through the pavement structure. As shown in Fig. 2.1, a flexible pavement provides sufficient thickness for load distribution through a multilayer structure so that the stresses and strains in the subgrade soil layers are within the required limits. It is expected that the strength of subgrade s

9、oil would have a direct bearing on the total thickness of the flexible pavement. The layered pavement structure is designed to take advantage of the decreasing magnitude of stresses with depth.A rigid pavement, by virtue of its rigidity, is able to effect a slab action to spread the wheel load over

10、the entire slab area, as illustrated in Fig. 2.1. The structural capacity of the rigid pavement is largely provided by the slab itself. For the common range of subgrade soil strength, the required rigidity for a Portland cement concrete slab (the most common form of rigid pavement construction) can

11、be achieved without much variation in slab thickness. The effect of subgrade soil properties oil the thickness of rigid pavement is therefore much less important than in the case of flexible pavement.|(a) Typical Cross Section of Flexible Pavement (b) Load Transmission in Flexible PavementHighway Pa

12、vementAirportPavementWheel LoadTack CoalPrime CoatWearing CourseBinder Course1-2 In2-4 in3-6 inBase Course4-12 in6-12 inSubbase Course12-18 inPrepared SubgradeMM*Natural Subgrade&24 in12-36 in12-60(1 in =25.4 mm)Concrete Slab6-12 In10-24 inBase or Subbase4-6 in4-12 inPrepared SubgradeG-12ln9-18

13、inNatural Subgrade1 In = 254 mm)(c) Typical Cross Section of Rigid PavementHighway Airport Pavement Pavement(d) Load Transmission in Rigid PavementWheelFIGURE 2.1 Flexible and rigid pavements.2.2 Layered Structure of Flexible Pavement2.2.1 Surface CourseIn a typical conventional flexible pavement, k

14、nown as asphalt pavement, the surface course usually consists of two bituminous layers 一 a wearing course and a binder course. To provide a durable, watertight, smooth-ridings and skid-resistant traveled surface, the wearing course is often constructed of dense-graded hot mix asphalt with polish-res

15、istant aggregate. The binder course generally has larger aggregates and less asphalt- The composition of the bituminous mixtures and the nominal top size aggregates for the two courses are determined by the intended use, desired surface texture (for the case of wearing course), and layer thickness.

16、A light application of tack coat of water-diluted asphalt emulsion may be used to enhance bonding between the two courses. Table 2.1 shows selected mix compositions listed in ASTM Standard Specification D3515 1992- Open-graded wearing courses, some with air void exceeding 20%, have also been used to

17、 improve skid resistance and reduce splash during heavy rainfall by acting as a surface drainage layer.2.2.2 Base CourseBase and subbase layers of the flexible pavement make up a large proportion of the total pavement thickness needed to distribute the stresses imposed by traffic loading. Usually ba

18、se course also serves as a drainage layer and provides protection against frost action. Crushed stone is the traditional material used for base construction to form what is commonlv known as the macadam base course. In this construction, choking materials consisting of natural sand or the fine produ

19、ct resulting from crushing coarse aggregates are added to produce a denser structure with higher shearing resistance. Such base courses are called by different names, depending on the construction method adopted.Dry-bound macadam is compacted by means of rolling and vibration that work the choking m

20、aterials into the voids of larger stones. For water-bound macadam, after spreading of the choking materials, water is applied before the entire mass is rolled. Alternatively, a wet-mix macadam may be used by premixing crushed stone or slag with a controlled amount of water. The material is spread by

21、 a paving machine and compacted by a vibrating roller.Granular base materials may be treated with either asphalt or cement to enhance load distribution capability. Bituminous binder can be introduced by spraying heated asphalt cement on consolidated and rolled crushed stone layer to form a penetrati

22、on macadam road base. Alternatively, bituminous road bases can be designed and laid as in the case for bituininous surface courses.Cement-bound granular base material is plant mixed with an optimal moisture content for compaction. It is laid by paver and requires time for curing. Lean concrete base

23、has also been used successfully under flexible pavements.TABLE 2.1 Example Composition of Dense Bituminous Paving MixturesMix Designation and Nominal Maximum Size of AggregateSieve Size2 in.(50 mm)1 妁 in,(37.5 mm)1 in.(25.0 mm)3/4 in.(19,0 mm)1/2 in.(125 mm)3/8 in.(9,5 mm)2% in1002 in.90-10090-10010

24、01 妁 in.90-1001001 in90-1001003/4 in.51090-1001001/2 in.35-6556-8090-1001003/8 in.56-8090-100No, 417-4723-5329-5935-6544-7455 - 85No. 810-361S-41144523-4928-5832-67No. 16No, 30No. 503-154-16S-175-195-217-23No. 100No, 2000-50-61-72-S2-102-10Note: Nviinbers in table refer to percent passing by weightS

25、昭ASTM» Standard Specification D3515-AnBook ofATMStandards. VbL 04.03 Road and Paving Materials; Travelled Surface Characteristics, 1992 With permission.223 Subbase CourseThe subbase material is of lower quality than the base material in terms of strength, plasticity, and gradation, but it is su

26、perior to the subgrade material in these properties. It may be compacted granular material or stabilized soil, thus allowing building up of sufficient thickness for the pavement structure at relatively low cost. On a weak subgrade it also serves as a useful working platform for constructing the base

27、 course, subbase course may be omitted if the subgrade soil satisfies the requirements specified for subbase material.224 Prepared SubgradeMost natural soils forming the roadbed for pavement construction require some form of preparation or treatment. The top layer of a specified depth is usually com

28、pacted to achieve a desired density. The depth of compaction and the compacted density required depend on the type of soil and magnitudes of wheel loads and tire pressures. For highway construction, compaction to 100% modified AASHTO density covering a thickness of 12 in. (300 nun) below the formati

29、on level is commonly done. Compaction depth of up to 24 in. (600 mm) may be required for heavily trafficked pavements. For example, in the case of cohesive subgrade, the Asphalt Institute 1991 requires a minimum of 95% of AASHTO T180 (Method D) density for the top 12 in. (300 mm) and a minimum of 90

30、% for all fill areas below the top 12 in. (300 mm). For cohesionless subgrade, the corresponding compaction requirements are 100 and 95%, respectively.Due to the higher wheel loads and tire pressures of aircraft, many stringent compaction requirements are found in airport pavement construction.In so

31、me instances it may be economical to treat or stabilize poor subgrade materials and reduce the total required pavement thickness. Portland cement, lime, and bitumen have all been used successfully for this purpose. The choice of the method of stabilization depends oil the soil properties Improvement

32、 expected, and cost of construction.2.3 Rigid PavementRigid pavements constructed of portland cement concrete are mostly found in heavy-traffic higiiways and airport pavements. To allow for expansion, contraction, warping, or breaks in construction of the concrete slabs, joints are provided in concr

33、ete pavements. The joint spacing, which determines the length of individual slab panels, depends on the use of steel reinforcements in the slab. The jointed plain concrete pavemen (JPCP), requiring no steel reinforcements and thus the least expensive to construct, is a popular form of Construction-

34、Depending on the thickness of the slab, typical Joint spacings for plain concrete pavements are between 10 and 20 ft (3 and 6 in). For slabs with joint spacing greater than 6 in, steel reinforcements have to be provided for crack control, giving rise to the use of jointed reinforced concrete pavemen

35、ts (JRCP) and continuously reinforced concrete pavements (CRCP). Continuously reinforced concrete pavements usually contain higher than 0.6% steel reinforcement to eliminate the need to provide joints other than construction and expansion joints.The base course for rigid pavement, sometimes called s

36、ubbase, is often provided to prevent pumping (ejection of foundation material through cracks or Joints resulting from vertical movement of slabs under traffic). The base course material must provide good drainage and be resistant to the erosive action of water. When dowel bars are not provided in sh

37、ort jointed pavements it is common practice to construct cement-treated base to assist in load transfer across the joints.3. Considerations for Highway and Airport PavementsThe two pavement types, flexible and rigid pavement, have been used for road and airport pavement constructioiL The choice of p

38、avement type depends on the intended functional use of the pavement (such as operating speed and safety requirements), types of traffic loading, cost of construction, and maintenance consideration.The main differences in design considerations for highway and airport pavements arise from the characte

39、ristics of traffic using them. Over the typical design life span of 10 to 20 years for flexible pavements, or 20 to 40 years for rigid pavements, a highway pavement will be receiving highly channelized wheel load applications in the millions. Consideration of the effects of load repetitions 一 such a

40、s cumulative permanent deformation, crack propagation, and fatigue failure 一 becomes important. The total number of load applications in the entire design life of a highway pavement must therefore be known for pavement structural design. In contrast, the frequency of aircraft loading on airport pave

41、ment is much less. There are also the so-called wander effect of aircraft landing and taking off and the large variation in the wheel assembly configurations and layout of different aircraft. These make wheel loading on airport pavements less channelized than on highway pavements. Identification of

42、the most critical aircraft is therefore necessary for structural design of airport pavements.Another important difference is in the magnitude of wheel loads. Airport pavements receive loads far exceeding those applied on the highway. An airport pavement may have to be designed to withstand equivalen

43、t single wheel loads of the order of 50 t (approximately 50 tons), whereas the maximum single wheel load allowed on the road pavement by most highway authorities is about 10 t (approximately 10 tons). Furthermore, the wheel tire pressure of an aircraft of about 1200 kPa (175 psi) is nearly twice the

44、 value of a normal truck tire. These differences greatly influence the material requirements for the pavements.公路和机场路面设计（节选）T. F. Fwa新加坡国立大学1緒论路面的设计和建造是为了能够给行人和货物在其上面进行全天候持久的安 全迅速活动提供一个舒适合意的水平环境。路面的这些功能要求可以通过在设 计和施工过程中仔细考虑如下几个方面来实现：（a）合理选择路面类型；（b） 合理选择各路面层材料和路基土处理；（c）合理进行各路面层厚度划分；（d）地 下排水系统设计；（e）路面排

45、水系统和几何尺寸设计；（f）路面的抵抗能力。公路和机场路面在结构设计上的两个主要考虑因素是材料设计和厚度设 计。材料设计要合理选择各路面层材料，满足沥青混合料（柔性路面）或者水 泥混凝土（刚性路面）配合比设计要求。这些问题将在本手册的其他章节中进 行讨论。本章介绍路面厚度设计的概念和方法。顾名思义，厚度设计是指确定 每个路面层的厚度，形成一个稳定的路面结构，使得在规定的设计年限内满足 设计交通量的要求。排水系统设计可检验整个路面结构在它的排水要求和一体 化设施方面是否满足相关要求。2.路面类型和材料2.1柔性路面和刚性路面传统上，根据通过路面结构传递到路基土上的交通荷载，路面分为两类， 即柔性

46、路面和刚性路面。如图2.1所示，柔性路面具有足够的厚度来承受多层结 构传递的分布荷载，使得路基土层的应力应变值控制在容许范围内。柔性路面 地基土的强度将直接关系到总厚度。路面结构层的设计充分利用到了应力随着 土层的加深而减少这一原理。刚性路面依靠其刚度，能够有效传递作用在整块混凝土板块上的车辆荷载, 如图21所示。刚性路面的结构承载力大部分都是由混凝土板块自身提供。在地 基土强度的一般变化范围内，硅酸盐水泥混凝土面板（最常见的刚性路面结构）的刚度要求无需板块厚度发生多大变化就能满足。因此，路基土性能对刚性路 面厚度的影响要比柔性路面小得多。(a)柔性路面横藪面粘结层一透层一磨耗层联结层基层底基

47、层聿土夯实层夫然路基1-2 in3-6 in/ 2-4 in/ 4-12 in6-12 in12-18 in12-36 in/ / 6-24 in12-60 n/(b)荷载在柔性路面的传递公路路面机场路面(1 in = 25.4 mm)公路路面机场路面-轮载混凝土板& 12 In10-24 In基层或者底基层4-6 In4-12 inn tut n素土夯实层6-12 in9-18 in天然路基(1 in = 25.4 mm)(c)刚性路面横截面(d)荷栽在刚性路面的传递图2.1柔性和刚性路面2.2柔性路面结构层次2.2.1面层沥青路面是一种典型的传统柔性路面，它的面层通常由两个沥青层组

48、成， 即磨耗层和联结层。为了保证路面的耐久性、不透水、平稳行车和防滑，磨耗 层一般由热拌沥青混凝土和耐磨碎石组成，而联结层则一般由大量的碎石和少 量的沥青组成。这两层的沥青混合料的组成以及骨料的最大公称直径是由使用 目的、所希望的表面结构(针对磨耗层而言)、层厚来决定的。由水稀释乳化沥 青组成的粘结层的一个简易运用就是增强磨耗层和联结层之间的粘结性。表2.1 显示了列在ASTM标准规格D35151992上的经选定的混合成分。有些空隙率 超过20%的开级配磨耗层也可作为强降雨天气时的地面排水层，用于提高抗滑 性和防止溅水。2.2.2基层柔性路面的基层和底基层占总路面厚度的大部分，它们用来分配交通

49、荷载 所产生的应力。通常基层也可作为排水层，并提供保护免受霜冻作用。碎石是 基层施工的常用材料，构成俗称的碎石基层。在本阶段施工过程中，填充材料 选用天然砂或者良好级配的压碎碎石集料，形成具有更高抗剪承载力的密实结 构。根据施工方法的不同，这样的基层有不同名称。2.1浓沥青摊铺混合料组成示例组合名称和碎石的最大公称粒径筛孔尺寸2 in.(50 mm)1 妁 in,(37,5 mm)1 in.(25.0 mm)3/4 in.(19mm)1/2 in.(125 mm)3/8 in.(9,5 mm)2% i口1002 in.90-10090-1001001妁id90-1001001 in.6D90-

50、1001003/4 in.52 in.35-6556-8090-1001003/8 in.56090-100No, 417-4723-5329-5935-65447455-85No. 810-361S-41144523-4928-5832-67No. 16No, 30No. 503-154-165-175-195-217-23No. 100No, 2000-5461-72-82-102-10注：表中数据指的是通过筛孔重虽百分比。文献：ASTM,标准规范D3515-84,ASTM标准年鉴，4. 03卷一道路和摊铺材料；行车 路面待性，1992。许可。干结碎石通过轧制和振动，使填充料填塞到大块石头间的空隙，达到压实 的目的。而对于水结碎石，在填充材料填塞空隙后，水在整块被轧制前就得到 应用。另外，通过用适量的水预拌碎石或矿渣，湿混碎石也可被使用。这些材 料先用摊铺机摊铺，然后再用振动压路机压实。颗粒基层材料可选用沥青或者水泥以提高荷载分配能力。为建造渗透碎石 路面基层，在固结并压实的碎石层上面喷洒热拌沥青混凝土时可采用沥青结合 料。沥青路面基层的设计和摊铺可以作为沥青面层的示例。水