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1、道路与桥梁专业英语课后句子特别感谢:付玉强、刘健、刘明金、刘鑫宇、宁维回、孙清龙第四课课文this force prevents the cracks from developing by eliminating orconsiderably reducing the tensile stresses at the critical sections at servicesload, thereby raising the bending, shear and torsional capacities of thesections.这种力能消除或大大减少使用荷载在跨中及支座等临界截面处产生的拉
2、应力,阻止裂缝出现,从而提高截面的抗弯、抗剪和抗扭能力。although it might appear that the blocks will slip and vertically simulateshear slip failure, in fact they will not because of the longitudinal force p.虽然看起来好像块体会滑移并发生垂直剪切滑动破坏,但事实上由于 纵向力p的作用,这种情况不会出现。but again, because of the compressive prestress imposed by themetalbands
3、 as a form of circular prestressing, they will remain in place.但乂是由于金属箍施加的压应力产生了环形预应力,因而木桶仍保持原样。linear prestressing had progressed a long way from the early days.线预应力从出现以来,已经有了很大的发展。the success in the development and construction of all these structures has been due in no small measure to the advanc
4、es in the technology of materials, particularly prestressing steel, and the accumulated knowledge inestimating the short and long-term losses in the prestressing forces.所有这些结构物的建造成功,在很大程度上应归功于材料技术的进步,也应归功于预应力损失计算方法的不断究善。阅读材料according to the aashto technology implementation group, hpc, whichis concre
5、te thathas been designed to be more durable, and, if necessary,stronger than conventional concrete, can help highway agencies to buildbridges that are better able to hold p to traffic and environmental demands.根据美国各州公路与运输工作者协会技术实施部的论述,高性能混凝土是一种经过设计后耐久性更好,强度比常规混凝土更高的混凝土(必要时),公路部门可以用其修建承受更人车辆荷载和更高环境要求
6、的桥梁。the section of mix proportions is the process of choosing suitableingredients of concrete and determining their relative quantities with theobject of producing as economically as possible concrete of certain minimumproperties, notably strength, durability and a required consistency.混合料配合比设计是在最经济
7、而满足强度、耐久性与所需稠度最低性能要求的目标下?选择适宜的混凝土组分并确定其相对数量的过程。generally, these methods are based on fundamental functions:water-to-cement ratio the constancy of water demand and theory of optimumaggregates proportioning, all of which determine mixtures with the required properties.这些方法通常都是基于如下基本公式进行的:水灰比、恒定用水量与集料最
8、佳配合比理论,他们确保混合料能满足相应的性能要求。silica fume is also often used in ternary combinations with portlandcement with fly ash or slag.硅粉通常与水泥屮的粉煤灰和矿渣形成三组分结构。the stress-strain behavior is depended on a number of parameters whichinclude material variables such as aggregate type and testing variables such asage at
9、testing, loading rate, strain gradient and others.应力应变性能取决于各种参数的取值,包括集料类型等材料变量以及试验龄期、加载速率、应变梯度与其他各种试验变量。lesso n 5结构设计原理 the successful designer is at all times fully conscious of the variousconsiderations that were成功的设计者在任何时候都能全面的考虑到结构初步设计中包含的各种因素,同时还充分考虑到以后施工中可能遇到的各种问题。特别感谢:付玉强、刘健、刘明金、刘鑫宇、宁维回、孙清龙 t
10、hen comes the analysis (or computation) of the internal gross forces(thrust,shears, .然后开始分析(或计算)由荷载、温度、收缩、徐变或其他设计因素引起的总内力(推力、剪力、弯矩和扭矩)、应力强度、应变、变形及反力等。 the criteria used to judge whether particular proportions will result inthe desired behavior用来评价拟定的(结构)尺寸是否会获得预期性能的准则反映了知识的积累(包含理论、现场试验、模型试验和实践经验)以及直
11、觉和判断力。 for most common civil engineering structures such as bridges andbuildings, the usual”.对大多数诸如桥梁和房屋建筑之类的土木工程结构,过去的常规做法是根据以下方法来进行设计,即把允许应力强度和那些由正常使用荷载和其他设计因素所产生的应力强度作对比。 depending on the type of structure and conditions involved, thestress intensities computed.根据结构类型和设计条件,在实际结构的分析模型中由假定的设计条件所计算的
12、应力强度与实际结构在实际设计条件中所产生的应力强度可能完全一样,也可能不一致。 the allowable-stress approach has animportant disadvantage in that it does not provide.允许应力法有一个严重的缺陷,也就是它不能为各类结构及其构件给出统一的超载能力。 when proportioning is done on the strength basis,the anticipated service loading is first基于强度的结构比例一旦确定,预期的使用荷载首先乘以一个合适的荷载系数(大于1)。荷载系数
13、的大小由下列因素确定:荷载的不确定性;结构在其使用寿命期间荷载变化的可能性;对于荷载组合而言,也与特殊组合的可能性、频率以及持续性有关。 in recent decades, there has been a growing concern among manyprominent engineers that.最近几十年来,很多著名的工程师已经逐渐注意到,“安全系数”的定义不仅不适当,不符合实际情况,更糟糕的是,基于这种概念上的结构设计原理在很多情况下会导致过分保守,不经济的设计,而在有些情况下又会出现破坏概率太高的冒险设计。 they feel, therefore, that the va
14、riations of the load effects and thevariations of the structural因此,他们感到,荷载作用和结构抗力的变化应该用统计的方法研究,结构残留概率或结构正常使用概率也应估计出来。阅读材料结构分析 such models are based on idealizations of the structural behavior ofthe material and are,".这些模型是基于材料的结构特性理想化建立的,因此,在某种程度上不仅完美,这与建模时的简化假定冇关。 structural design involves th
15、e arrangement and proportioning ofstructures and their ".结构设计包含结构布置和结构及其构件的尺寸设计。所形成的结构应该能够在整个使用年限内,承受允许范围内的设计荷载。 variable loads are also referred to as live (or imposed) loads, andinclude those caused by.".可变荷载亦指活载(或冲击荷载),同时还包含除移动荷载(如车辆、火车等)之外,由施工作业、封、地震、学、爆破以及温度变化引起的荷载。 a structure that i
16、s initially at rest and remains at rest when actedupon by applied loads is.当结构处于静止状态,以及在使用荷载作用下仍处于静止状态时,(我们)称该结构处于平衡状态。第八课the basic principle for locating highways is that roadway elements suh ascurvature and grade must blend with each other to produce a system thatprovides for the easy flow of traf
17、fic at the ddesign capacity,while meetingdesign criteria and safety standards定线的基本原则是车行道要素如巧道和坡度必须互相结合,在满足设计规范和安全标准的要求的同时,提供满足设计通行能力并且平稳的交通流体系for example,if it is found that a site of historic and archeologicalimportance is located within an area being considered for possible routelocation,it maybe
18、immediately decided that any route that traverses that sitashouldbe excluded from further consideration特别感谢:付玉强、刘健、刘明金、刘鑫宇、宁维回、孙清龙例如,如果发现一个重要的历史古迹和建筑位于路线可能通过的区域,则应立即确定通过那个区域的任何路线下一步将不被考虑the availability of computer-based techniques has significantly anhancedthis process since a proposed highway can
19、be displayed on a monitor, enabling the designer to have a drivers eye view of both the horizontal and vertical alignments of the road计算机技术极大地提高了定线过程(的效率),因为设计的公路可以显示在屏幕上,从而使设计者有了驾驶者的实现效果,即可以看到平面线形,又可以看到纵面线性most arterials have 12-ft travel lanes since the xtra cost for constructing12-ft lanes over 1
20、0-ft lanes is usually offset by the lower maintenance cost forshoulders and pavement surface, residing in thereduction of wheelconcentrations at the pavement edges大多数干线车行道宽12英尺,因为修建12英尺车行道比10英尺车行道超出费用通常被路肩和路面较少的养护费抵消了,可以减轻路面边缘的轮载集中现象the usable width is the same as the graded width when the side slop
21、e isequal to or flatter than 4;l,as the shoulder break is usually rounded to a widthbetween 41 and 6 ft,thereby increasing the usable width当边坡等于或环宇4:1 (水平距离:竖直距离)时,有效路肩宽度与整型路肩宽度相等,因为路肩的转折处通常被修成圆形,宽度达到4-6英尺,因此增加了有效宽度the usable median shoulder width for divided arterials with three ormore lanes in eac
22、h diection should be at least 8ft, since drivers in difficulty onthe lane next to the median often find it difficult to maneuover to the outsideshoulder when there is need to stop对于每一方向有三车道或者更多车道的分离式干线公路,中间带的有效路肩宽度至少应有8英尺,因为紧靠屮间带车道上行驶的驾驶者出现问题需要停车时,很难行驶到外边的路肩上。some disadvantages associatedwith raised
23、 medians include possible loss of control of the vehicle by the driverif the median is accidentally struck ,and they cat a shadow from oncomingheadlights, which results in drivers finding it difficult to see the curb凸起式中间带也有一些缺点,如若司机不幸撞上中间带,车辆可能会失控,对想车前灯照射下中间带的阴影会使驾驶者难以看到路缘石。第十一课l. the wearing surfa
24、ce of a rigid pavement usually is constructed ofportland cement concrete such that it acts like a beam.刚性路面的磨耗层通常用水泥混凝土铺筑,其受力与梁类似,.high-type pavements have wearing surfaces that adequately support theexpected traffic load without visible distress due to fatigue and are notsusceptible to weather cond
25、itions .高级路面的磨耗层能奋效的承担预期的车辆荷载,而不会出现明显的疲劳破坏,并且不易受气候的影响。well compacted to prescribed specifications.充分压实达到规范的要求it should be capable of withstanding high tire pressures,resisting theabrasive forces due to traffic,providing a skid-resistant driving surface,andpreventing the penetration of surface water
26、into the underlying layers.表面层应该能够承受高的轮胎压力,能够抵抗车辆的摩阻力,提供良好的抗滑表面,并能阻止表面水渗入下承层。in some cases, the transverse joints of plain concrete pavements areskewed about 4 5ft in plan,such that only one wheel of a vehicle passesthrough the joint at a time.在有些情况下,素混凝土路面的横向接缝做成倾斜4-5英尺(平面上),这样,在某一时刻只有一个车轮通过接缝。l.lt
27、 is usually assumed that the subgrade layer is infinite in both thehorizontal and vertical directions, whereas the other layers are finite in thevertical direction and infinite in the horizontal direction.通常,假定土层在水平方向及垂直方向均为无限,而其他结构层垂直方向有限,水平方向无限。2. because the accumulated repetitions of traffic loa
28、ds are of significantimportance to the development of cracks and permanent deformation of the pavement.因为累计重复荷载对路面裂缝的发展以及永久变形会产生重要的影响。特别感谢:付玉强、刘健、刘明金、刘鑫宇、宁维回、孙清龙3. for example,traffic wheel loads will induce flexural stresses that aredependent on the location of the vehicle wheels relative to edge o
29、f thepavement, whereas expansion and contraction may induce tensile andcompressive stresses, which are dependent on the range of temperaturechanges in the concrete pavement.例如,车轮荷载会引起弯拉应力,其大小取决于车轮与路面边缘的相对位置,而温度胀缩则可能引起拉应力与压应力,其大小取决于混凝土路面内温度变化的幅度。4compressive and tensile stresses are therefore induced
30、 at the top andbottom of the slab, respectively , during the day,wherea tensile stressrs areinduced at the top and compressive stresses at the bottom during the night.因此在白天,板顶和版底分别受压和受拉,而夜晚板顶受拉板底受压。5. different types of joints are placed in concrete pavements to limit thestresses induced by temperat
31、ure changes and to facilitate proper bonding oftwo adjacent sections of pavement when there is a time lapse between theirconstruction (for example, between the end of one day's work and thebeginning of the next.)混凝土路面内设置了不同类型的接缝来减少温度变化引起的应力,当两个相邻板块施工中断时(例如,某f1的最后施工部分和次日的初始施工部分),需要采取措施形成冇效的连接
32、。第十五课1. the proposed alignment of the highway to be constructed along withthe drainage, utility and geotechnical information provided should bereviewed and a site should be considered essential.应审查拟建公路的推荐线位、沿线的排水、公共设施以及土工技术资料,实地考察也是必需的。2. technology is available to feed information of the various co
33、urses to anonboard computer that assists the operator of grading equipment to finishwithin millimeters of the planned elevation.将各层的高程数据输入车载电脑,它将辅助道路平整设备的操作人员工作,成型误差在几毫米范围内,这种技术己经实现了。3. where good material sources are easily available, embankmentmaterials falling between the classification of a-l-a
34、and a-4 per aashto m145are preferred.该规范将土按实验室测定的粒径分布、液限与塑性指数分为七大类,每一大类分为若干小类。4. care should be taken to ensure that these large size materials do notnest to create large voids that could become detrimental to the performanceof the embankment due toexcessive settlement.应注意确保大粒径材料不会聚稅在一起而形成打的空隙,这些空隙由
35、丁可能产生过大的沉降,对路堤的性能是有害的。5. an accelerated construction schedule sometimes does not allow forthe use of traditional surcharge of soft subgrade soils and sufficient time forconsolidation settlement to be completed.工程进度紧张时,就没有足够的时间让软土地基完成固结沉降,不能使用传统的堆载法。6. base course material section is generally carrie
36、d across underneath theshoulders or curb and gutters to not only provide a stable base but also toensure continuity for drainage, away from the surface course of the pavementsection.路妞中的基层材料通常超出妞层延伸至路肩或路缘与边沟下部,不仅可以提供稳定的基础,而且可以确保排水的连续性。l. laydowen operations include determination of means to form thesection, given the volume, location and other existing conditions such as bloc
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