桥梁外文翻译.doc

翻译原文
关键词：桥梁；河堤；土工布；膜与土工格栅
英国锁城大桥
一、 引言
本文描述的是在受限制地区用最小的费用修建一座铁路桥梁使之成为开放的住宅发展区。锁城地区是位于住宅发展十分紧张的韦斯顿超
马雷的东部。监督桥梁建设的客户是城堡建设有限公司，它由二大房建者组成。该区的规划局是北盛捷区议会（NSDC）。该发展地区被分为布里斯托尔和埃克塞特。规划条件规定，直到建成这条横跨的铁路大桥为止，该地区南部区域不可能适应居住。可见锁城大桥的建成对该地区发展的重要性。
客户的工程师、工程顾问、一般设计原则和初步认同原则下(AIP)与NSDC发出投标文件。
该合同在2000年7月1授予安迪。投标价值1.31亿美元，合同期定为34周，到2001年4月完成。
二、地基
在招标阶段佩尔研究了一些优化设计和招标后的裁决计划进行了充分的经济分析后交付承包商，院长及安迪 。原来设计要求H型
钢桩柱下的桥台地区与相邻铁路线之间必须是垂直运动。经审查后的地面条件和根据以往的经验判断，现浇位移桩，使用其他类似地方的河堤下，可驱动更接近轨道而不会有任何问题。并在受影响区域进行了监测，打桩作业和水平高程的变化小于要求的6毫米。
在地面下覆盖厚达19米的软冲积土。这下面是2米层坚定/硬粘土泥岩或砂岩基石。两种类型的驱动现浇桩设计了340和380毫
米的大口径水管，以应付不同载入条件所造成的桥梁和堤坝的不同荷载。 这些有利于桩体的载入。最多可达一天8个桩的记录。总长度
驱动介于22和24米之间。试验证实了完整的设计和表示最多解决在工作负荷为六毫米
三、荷载传递，路基
桩被用来抑制端口的负载转移，这是因为修建时采用了石头和网膜。 在招标图纸上显示了基础顶部扩大桩，再运用早先经验， 佩尔指出这个设计方法可能被运用减少垫层的深度，并且把这种方法使用在城堡大桥上。 通过熔铸一个扩大的部分1.1m在每桩上面，距离到桩下减少了1 m直径，并且薄膜的间距在垫层的增加因而被减少了。 假设成拱形的作用在承台依靠角度458从堆到垫层的上面，可能相应地减少石头的深度。通过合理的设计，垫层的整体深度从1500毫米减少了到900毫米。 这样减少了挖掘深度并保留了原始的底层。.
垫层路堤上升到最大高度6.3 m的车道高程。为了减少蔓延的路堤，招标设计最初面临混凝土预制板垂直侧壁。这是后来修正的在投标阶段用红砖砌筑的垂直墙壁，迫使改变设计中的钢筋路堤。路基被分包两个部分以坦萨为基础和规范发展的佩尔弗里斯赫曼恩路段。其系统组成的单轴土工格栅在不同规定垂直间隔的压实颗粒物质。颗粒状材料，符合高速公路规范做路堤材料的相关规定。该网格，挂靠在干燥的混凝土砌块上形成近垂直的路堤。被垂直排水层分开。在两者之间安装了隔水带并且在前面修建了砖砌饰面。
四、桥梁和桥墩
桥面包括预制预应力混凝土梁和一块跨度20m的现浇钢筋混凝土平板。图4和5显示桥梁的长度和横断面。 在加强的桥台建立支撑梁。在支撑梁区域凸显了桥台狭窄的特点，并且这些太狭窄的桥台
不能避免的退出工作结构，并对混凝土砌块侧壁的河堤产生压力。为了克服这个困难，把河堤的挡土墙在桥台附近扩大，并使之成为完全挡土墙 (图8)。 因为这变动太大以至于不能掩藏，在砖墙的上面放置的砖砌和预制混凝土做了加宽的区域，并在桥台附近形成了坝肩。最后的布局给桥梁带来了增值效应并丰富了桥梁和其施工方法。
一旦浇注了混凝土，整个桥面将形成一个整体。 这方法消除了梁与支撑之间的转动，因此，使桥面形成了一个统一的更加陡峭坡度。为了保持桥面产生压力保持一样，使桥面出现横向的排水，这是招标图纸不允许的。 这就提出了一个南部路基高于预期150毫米。
设计要求在梁和桥面板之间容纳一些复杂的服务设备。这些设备是一条250毫米直径总水管(通过一条350毫米直径输送管)， HV电缆和一条四种方式的BT输送管。在招标图纸上看这些服务设备是在桥梁之间缺失的部分通过，而不是在它的下面通过。这些可利用的部分损失能够使桥梁的自重更小、结构减轻，而且桥梁的截面尺寸更大，这些临时的设施在孔中通过。因此，要求作出详细的安装说明，这又是一个非常棘手的工作。
桥梁的布局方案是一个整体的固定结构。并且，重新设计成了垂直路线，以适应桥面的变化。这就导致了南部桥台的升高从而，桥面的坡度增加。因此，对上面的桥梁产生了连锁反应。为提供合理的桥面跨越坡度，在桥南部的桩相应的增长，在增长最多的地方增加深度超过300毫米。这要求在预应力混凝土中增加更大预应力。
五、护墙
标准型的P2护墙的目的是保护的边缘河堤。因此，对该小组提出了相当大的挑战。必须在原先的位置浇注钢筋混凝土，承包商对这种解决方案提出了健康与安全问题，因为在地面上浇注6m的边缘梁是十分危险的，必须要用到更多的脚手架和永久模板，并且，施工将延长几个星期，工期将更加紧张。
为此，承包商建议使用预制混凝土栏杆来替代在原处浇注混凝土。然而，由于桥梁采用的是最小半径，所以每个混凝土梁的长度受到限制，以避免出现外观问题。并且计算表明混凝土栏杆会受到使用限制。
另外一种折衷的解决办法包括一个预制件和边缘现浇的行人/自行车道建设，最终克服了这些问题。为了实现理想的效果，边梁的预制需要的足够的大小和形状的砖块，以确保边缘的路堤稳定。此外，双方每个单位将需要略锥形，以适应半径的弯道，并且护墙后螺栓支持摇篮要预先安装在正确的间距上。由于设计师和承包商通力合作，盘区类型的数量从30减少到17，排列在长度从最多3.65 m减少到最小限度1.98 m，并保留栏杆位置恒定间距沿堤防的主要长度（如图9）。
预制的构件通过现场浇注在一起，形成了一个整体。同时连栏杆和扩大的路堤也浇注在一起。把桥面板浇注在一起，使之形成梁。并且桥面板做了脚趾形设计，利用其摩擦力来抵抗栏杆的偶然荷载，用连续的桥面板和悬臂式结构抵抗外部的对 桥面的扭转和倾覆力。
P2支持部分被做成水平并且与桥梁完美的组合在一起。而末端被混凝土掩盖保证了外观的整洁。
六、运作
在整个计划中最值得欣慰的是能够很好的维护各个方面的关系。大家在工程合同约定下一起工作，在出现矛盾之前，举行定期会议时告知承包商、设计师、客户的工程师和客户的建筑师工程之间相互通告事情的最新事态发展和处理的意见。并且在感兴趣的方面打开信息交换的通道适时的通信，例如处理好铁路轨道等，并按要求保证资金适时到位。在遇到工程最后期限紧张时或发现设计图纸有小遗漏时要以专业的方式进行沟通。这事成为承包商在整个合同期间维护信用的关键。
七、摘要
锁城大桥是集现代和创新于一体的设计（图9）。加上其美丽的外观，不仅美化了当地环境。还增加了外界联系。更有利于新住宅的发展。并且在桥的南部还建立了一个公园，这将提高大桥的地位和整体的外观。在今后几年里，锁城大桥将是所有参与建造者的自豪。

参考文献
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Castle Bridge, Weston-Super-Mare, UK
1. INTRODUCTION
This paper describes a minimal-cost solution to a road bridgeover a railway, on a restricted site, to open up land for residential development. Locking Castle is an area under heavy residential development on the eastern side of Weston-Super Mare. Overseeing the development and client for the bridge isLocking Castle Limited, a company owned in consortium by two major house builders. The planning authority is North Somerset District Council (NSDC). The development area is splitin half by the Bristol to Exeter main railway line. Planning conditions for the area stipulated that the southern area couldnot be inhabited until a crossing of this railway line had beenbuilt. Fig. 1 shows the Locking Castle development and theimportance of the bridge to the area.
The client’s engineer, Arup, agreed general design principlesand the preliminary Approval in Principle (AIP) with NSDCprior to the issue of tender documents.
The contract was awarded to Dean & Dyball in July 2000 for atender value of £1·31 million and the contract period was set at34 weeks for a completion in April 2001. A simplifiedprogramme is shown in Fig. 2.
2. GROUNDWORKS
During the tender stage Pell Frischmann looked at a number ofrefinements to the tender design and following the award of thescheme undertook a full value engineering exercise in conjunction with the contractor, Dean & Dyball. The
originaldesign called for steel H-piles under the bridge abutment areasadjacent to the railway line where limited vertical movement ofthe track was essential. Following a review of the groundconditions and based on previous experience, the team successfully argued that cast-in-situ displacement piles, usedelsewhere under the embankments, could be driven closer tothe tracks without any problem. The tracks were monitoredduring piling operations and level changes of less than 6 mmwere recorded along the affected section.
The ground conditions at the site consist of made groundoverlying up to 19 m of soft alluvial clay. Below this either a2 m layer of firm/stiff clay on mudstone or sandstone bedrockexists. Two types of driven cast-in-situ piles were designed byKeller, 340 and 380 mm in diameter, to cope with the differentloading conditions caused by the bridge and the embankment.These were driven to refusal from the existing ground level. Thepoor ground contributed to rapid pile installation and rates of up to eight piles a day were recorded. The total driven lengthranged between 22 and 24 m. Pile design information is shownin Table 1. Tests confirmed the integrity of the design andindicated a maximum settlement at working load of 6 mm.
3. LOAD TRANSFERMATTRESS AND EMBANKMENTS
The piles were used to support a load transfer mattress,which was constructed fromlayers of stone and geomembrane grids. Enlarged head piles had been shown on the tender drawing but, again drawing on previous experience, Pell Frischmann demonstrated that this design method could be utilised to reduce the depth of the
mattress and it was suggested that this approach be employed at Locking Castle. By casting an enlarged head of 1·1 m diameter at the top of each pile, the distance to the next pile was reduced and thus the span of the geomembranes in the mattress layers was decreased. Given that the arching effect in the mattress relies on an angle of 458 from the pile to the top of the mattress, the depth of stone could be reduced accordingly.
The overall depth of the mattress was reduced from 1500 mm to 900 mm by rationalising the design in this way. This also led to savings in reduced excavation to the original ground level (Fig.
3).Above the mattress the embankment rises to a maximum height of 6·3 m to carriageway level. To reduce the spread of the embankment, the tender design originally indicated faced precast concrete panels to vertical sidewalls. This was amended later in the tender stage to vertical walls of class A red brickwork, forcing a change in the design of the reinforced embankment. The design of the embankment was subcontracted to Tensar, based on a specification developed by Pell Frischmann. Their system comprised uniaxial geogrids laid at varying vertical spacing on compacted granular material. Class 6I/J granular material, in accordance with the Specification for Highway Works1was specified and this made up the bulk of the embankment. The grids were then anchored to dry-laid interlocking concrete blocks forming the near-vertical face of the embankment. A vertical drainage layer separated the 6I/J material from the concrete blocks. Ties were installed between the joints in the concrete blocks and the class A brickwork facing was constructed in front. Fig. 4shows the embankment crosssection.
4. BRIDGE AND ABUTMENTS
The bridge deck consisted of prestressed Y3 precast concrete beams and an in situ reinforced concrete slab spanning 20 mover the railway lines. Figs 5 and 6 show the long- and crosssection of the bridge. The beams were supported on bankseats founded on the reinforced embankments. The narrow nature of the embankments was accentuated at the bankseat area sand it was soon obvious that these were too narrow to avoidresting the structure on the concrete block sidewalls of theembankments. To overcome this, the embankments werewidened locally in the vicinity of the abutments to enable thebankseat to sit wholly on the embankment (Fig. 7). As this change was too large to hide, a feature was made of the widened area by the use of strong right angles in the brickwork and pre-cast concrete (PCC) flagstones laid around the top of the brick wall adjacent to the abutments. The final layout gave added effect and accentuated the bridge and its approaches.
Once placed, the PCC beams were cast into each bankseat by the addition of an integral endwall. This eliminated the need for bearings and movement joints, thus creating an integral and steeper gradients on the approach roads. Pressure to keep the deck construction as shallow as possible came also from the discovery that the original tender drawings had not allowed for a deck crossfall to shed water. This raised the southernembankment 150 mm higher than anticipated.
The design was further complicated by the requirement to accommodate services under the bridge deck, between the beams, and through the integral end wall. These services were a 250 mm diameter water main (through a 350 mm diameter duct), an HV electric cable and a four-way BT duct. The loss of section was overcome by agreement to run the electric cable over the top of the deck, rather than below it, as it was not
physically possible to bring it through the identified location on the tender drawings. The loss of available wall section led to the requirement for smaller numbers of, but larger diameter, bars fitted around the holes through the endwalls. This is turn made the detailing and fitting of these bars one of the trickiest elements of the job.
Although generally fixed by the layout of the overall scheme, the vertical road alignment was redesigned to accommodate the change in alignment of the bridge deck. This led to an increased gradient on the southern embankment but also had a knock-on effect on the loading of the bridge To provide a reasonable rollover across the deck from the steep gradients on either side, the depth of surfacing increased to over 300 mm at its deepest point. This greater loading increased the amount of prestressing in the PCC beams.
5. APPROACH EMBANKMENT PARAPETS
Standard parapets of type P2 were designed to protect the edges of the approach embankments and the support for these presented the team with a considerable challenge. Originally shown as in situ reinforced concrete, it soon became clear that this solution would provide the contractor with a significant health and safety problem. Casting edge beams 6 m above the ground was potentially dangerous, required a lot of scaffolding mand permanent formwork, and would add weeks to the tight construction programme.
To overcome this, the contractor proposed using precast concrete parapet supports in lieu of in situ. However, due to the tight centreline radii on the bridge approaches (50 m radius), the length of each PCC section would need to be limited to avoid a ‘threepenny piece’ appearance. This created its ownproblems when design calculations showed that accidental loadings on the parapet would not be restrained by the use of small discrete PCC units.
A compromise solution consisting of a precast edge piece and an in situ section under the footway/cycleway construction was eventually developed to overcome the problems. To achieve the desired effect, the precast edge beam would need to be of sufficient size and shape to rest on the brick/block edging of the embankment without being unstable. In addition, the sides of each unit would need to be slightly tapered to accommodate the radii of the bends, and the parapet support post bolt cradle would need to be pre-installed at the correct spacing. Team work between the designer and contractor led to a reduction in the number of panel types from 30 to 17, ranging in length from a maximum of 3·65 m to a minimum of 1·98 m, while keeping the parapet posts at a constant spacing along the main length of the embankments (Fig. 9).
The precast units were tied together by means of an in situ element. This comprised a slab extending the entire length of the embankments from the bankseats to the end of the parapet units. The slab was cast continuously, without joints, so that it acted as a beam. The slab was designed with a toe, which, together with friction, counteracts the lateral forces from accidental loading of the parapet posts while the overturning forces of any impact are countered by the weight and cantilever effect of the continuous slab. The P2 support sections were placed and levelled to give apleasing sweep and elevation to the bridge while a tail on the PCC unit was included to hide the top of the brickwork wall, ensuring a neat appearance was achieved.
6. TEAM WORKIN
One of the most pleasing aspects of the scheme was the goodworking relationship that was maintained between all parties. Although working under the General Conditions of Contract for Building and Civil Engineering GC/works/1,2the contractor was keen to espouse the ethics of partnering. Regular meetingsbetween the contractor, designer, client’s engineer and client’s architect took place to keep all parties informed of the latest developments and to deal with concerns before they became a distraction. Communications, channelled through the contractor, between interested third parties, such as Railtrack and NSDC, were also well managed, which ensured that possessions were granted as requested and adoption requirements were dealt with swiftly. This approach was key to meeting the tight construction deadline and in dealing with the minor omissions found in the tender design in a professional manner. It is a credit to the contractor that this was maintained throughout the period of the contract.
7. SUMMARY
Locking Castle Bridge is based on a modern and innovative design which, along with its appearance (Fig. 10), benefits the local environment and provides a focal point for the new residential development. The creation of a park adjacent to the southern embankment will enhance the status and appearance of the bridge in years to come and provide a sense of pride forall those involved in the construction of Locking Castle Bridge.

REFERENCES
1. Specification for Highway Works. In: Manual of ContractDocument for Highway Works. Highways Agency. TheStationery Office, 1993.
2. GC/Works/1: Conditions of Contract for Major Building and Civil Engineering W