The Longest Double-deck Suspension Bridge

2018-01-05ByLiuDongli

Special Focus 2017年12期

关键词：长江大桥大堤主塔

By Liu Dongli

Translation by Liu Jie

The Longest Double-deck Suspension Bridge

By Liu Dongli

Translation by Liu Jie

At 7:28 a.m. on November 21, 2017, the construction workers of the Yangsigang Yangtze River Bridge poured the last cubic meter of concrete,marking the successful completion of its main tower on Hanyang Bank. At this moment, the site became a sea of joy, and everybody was as happy as a lark.

On the other side of the river,Li Yongqi, a young man born in the 1980s, was all excitement,looking in the distance at the main tower which stood 231.9 meters high, which is similar to the height of an 80-storey building. In a month, the main tower on the south bank, which was in his charge, would also be completed as scheduled.

As the manager of the Second Project Department of the Yangsigang Bridge Project, Li Yongqi recalled what happened a year ago, while looking at the “giant” towering over the river.

August 12, 2016 was an important day. Every time someone referred to it,Li Yongqi would become extremely excited. “It just felt like I was in a dream,” he said.

On the afternoon of the day before, he had checked the subsidence of the open caisson of the bridge on the south bank in Wuchang.“Theoretically, the open caisson is supposed to sink 20 centimeters daily on average,”Li explained. “However, in reality it sometimes would be absolutely still for a fortnight in succession, which was most worrisome.” Since there was no sign that the open caisson would sink, he left in disappointment.

Unexpectedly, early the next morning, his mobile phone was ringing continuously to bring him the news that “the open caisson for the main tower of the bridge on the south bank had descended to the specif i ed position.” When they heard,all the people on the site went around spreading the good news, and the old experts of bridge engineering went out of their way to get there in a hurry, just to witness in person this great moment.

This surprise thrilled Li Yongqi so much that he couldn’t wait to put his excitement into a poem:

For a hundred and fi fty days and nights,

With the toil of lots of brothers,

The caisson of one hundred and twenty thousand tons

Sank to the bottom of the Yangtze River,

To be the foundation of the bridge

For a century long.

As the tenth Yangtze RiverBridge in Wuhan, the Yangsigang Bridge’s construction began on December 3, 2014. In order to not affect the traffic of the Yangtze River waterway, no piers would be constructed in the river.Instead, the bridge would cross the river directly with a span of 1,700 meters. As a result, it would become the longest double-deck highway suspension bridge in the world.

杨泗港大桥一号主塔封顶摄影/张卫东No.1 main tower of the Yangsigang Yangtze River Bridge sealed roof Photo by Zhang Weidong

2017年11月21日7时28分，随着建设者们将最后一方混凝土浇筑完毕，武汉杨泗港长江大桥汉阳岸主塔成功封顶。一时间，人人欢呼雀跃，热闹非凡。

对岸，80后小伙子李永旗隔江遥望这座高231.9米、相当于80多层楼高的主塔，心潮澎湃。一个月后，他负责的南岸主塔也将如期封顶。

作为杨泗港大桥第二项目部经理，李永旗看着屹立于江中的雄伟“巨人”，思绪回到一年前。

2016年8月12日。每当提起那一天，李永旗都异常兴奋：“简直就像做梦一样。”

就在前一天下午，他检查杨泗港大桥南岸（武昌）沉井下沉情况。“理论上来说，沉井平均一天下沉20厘米，但有时候会一连半个月纹丝不动，这是最让人煎熬和焦虑的。”而沉井没有下沉的迹象，他有点失望地离开。

没想到第二天天刚亮，他的手机便响个不停：“杨泗港大桥武昌南岸主塔沉井下沉到位。”收到喜讯，工地所有人奔走相告，桥梁界的老专家也不辞辛苦赶来，只为亲睹这一刻。

这突如其来的惊喜，让李永旗激动万分。他乘兴作诗一首：

一百五十日与夜，

数名弟兄汗和血。

十二万吨驻江底，

承载百年做根基。

2014年12月3日，作为武汉市第十座长江大桥，杨泗港长江大桥破土动工。为了不影响长江航道通行，桥在江中基本不设桥墩，采用“一跨过江”形式，跨度1700米。杨泗港大桥由此成为世界上跨度最大的双层悬索桥。

欲戴其冠，必承其重。作为世界之最，大桥在施工中遇到各种难题。

由于跨度大、车道多，作为“挑夫”的大桥南、北两座主塔必将承受更大的压力。建设者们将塔墩设计为椭圆形沉井基础，平面面积相当于8个篮球场的大小。

If one tries to wear the crown,he must bear the weight. Being one of the world’s greatest, the bridge had run into various diff i culties in its construction.

As the “bearers” of the bridge,the main towers on the two banks of the Yangtze had to be able to sustain greater pressure due to the bridge's long span and multiple traffic lanes. Therefore,the constructors designed the pylon pier as an oval open caisson foundation with a fl at area about the size of eight basketball courts.

The north main tower is only a few meters away from the levee of the Yangtze River. With such a huge “giant” sinking, if affected,the levee would easily sink, crack,and even burst.

Together with experts in bridge engineering, Chief Engineer Huang Feng and Project Manager Wei Zhengping from the First Project Department, as well as Manager Li Yongqi from the Second Project Department of the Yangsigang Bridge Project explored and probed into the problem. Finally they invented a C-shaped soldier-pile protective structure. They would have a protective wall built between the open caisson and the river levee, which could control the deformation of the fender piles of the levee down to the centimeterlevel. So, the safety of the levee and the buildings around the open caisson could be guaranteed t o t h e m a x i m u m d e g r e e.This “Protection Method for Construction in the Vicinity of a River” obtained a national patent for invention.

After the safety of the levee was guaranteed, they had tougher problems to tackle. The structural sites of the two towers on both banks were set on beds of hard plastic clay. On the one hand that meant the soil was as hard as rock, and on the other hand,it was more plastic than rock.So it would be impossible to employ the conventional digging method of explosion. Generally,when faced with such geology,the designers would have had to change their plan for the construction site, not to mention that the clay there ran as much as 6.2 meters deep, which could be the world’s deepest deposit of plastic clay encountered in bridgeconstructio

北岸主塔离长江大堤仅数米距离，这样一个“巨无霸”在下沉过程中一旦对大堤产生影响，极易引起大堤下沉、开裂，甚至溃堤。

杨泗港大桥第一项目部总工程师黄峰、项目经理韦正平，第二项目部经理李永旗等人联合桥梁专家们一起，探讨摸索，首创“C”字形排桩防护结构，在沉井与大堤间构筑一道防护墙，可将大堤防护桩在施工中的变形控制在厘米级，从而最大程度保障大堤和沉井周围建筑的安全。这一“江河临边施工防护方法”，获得国家发明专利。

大堤安全问题解决，还有更硬的骨头等着他们。大桥的南北两岸塔址处地质均为硬塑黏土层。这种土质硬如岩石，又比岩石有可塑性，无法采用爆破等常规方式。但凡遇到此类地质基础，设计者们都忍痛改变选址方案。而这里的黏土深达6.2米左右，堪称世界之最。

施工人员使出浑身解数，空气吸泥、水下爆破、高压射水、空气幕等等全用上，试图保证沉井的顺利下沉。最后，他们研发出射水压力是普通吸泥机25倍的多功能吸泥机，终于让坚硬的黏土变松、变散，让深井得以缓缓下沉。

即使有先进的工艺和设备，施工过程也不顺利。2号沉井下沉仅一两米不久，便被迫停止。蛙人下水摸查发现，地下有大量古树沉积，给深井下沉造成障碍。

江底怎会有古树？数量有多少？李永旗在图书馆连泡一个多星期，通过查找大量文献、地方志，终于得知，这里曾是一片树林，公元1700年间，由于长江改道，这片树林被淹没到江底，从此不见天日。

挖掘、清障、继续下沉……任何困难都阻挡不了工程安全顺利完成的决心。

他们的攻坚的汗水终于换来骄人的喜讯——

2016年5月23日，北岸（汉阳）沉井下沉到位；

2016年8月12日，南岸（武昌）沉井下沉到位；

2017年11月21日，北岸（汉阳）主塔成功封顶……整个工地沸腾了。它标志着这座世界上功能最全的大桥，拉开上部结构施工的序幕。

杨泗港大桥开创在硬塑黏土层建设沉井基础桥梁先河，为将来建设跨海大桥等大跨度桥梁提供宝贵借鉴，实现桥梁建设基础结构设计上的新突破。♦

杨泗港大桥建筑工地上，中铁大桥局打出口号“打造世界一流建桥国家队” 摄影/许溶丰“Building a world-leading national bridge construction team,” slogan of China Railway Major Bridge Engineering Group at the construction site of the Yangsigang Yangtze River Bridge Photo by Xu Rongfeng

小贴士：武汉杨泗港长江大桥由中铁大桥局施工建设，是武汉市第10座长江大桥，全长4.13公里。作为长江主轴上的超级工程，杨泗港长江大桥将是世界上功能最全的大桥，包括机动车道、非机动车道、人行道及人行观光休息区等多种功能设置。该桥预计2019年建成通车。

The constructors had tried every means possible to make the open caisson sink smoothly. In the end, they developed a multifunctional suction dredger with hydraulic pressure 25 times greater than that of the ordinary one. Then the hard clay became loose and dispersed, and the open caisson was able to sink little by little.

Even with advanced technology and equipment, the construction did not go smoothly. The No. 2 open caisson was forced to stand still after sinking for about one or two meters below. The frogmen dived into the water and found that the open caisson had been stopped because of a large deposit of old trees underground.

Why were there old trees at the bottom of the river? How many trees were there? Li Yongqi spent over a week in the library consulting a large amount of literature and local chronicles.Finally, he learned that there had been a forest there hundreds of years ago. And in 1700, because the Yangtze River rechanneled its course, the forest was fl ooded and sank to the bottom of the river.

从南岸江底挖掘出的古树摄影/李永旗Trunks extracted from the south bank of the Yangtze River Photo by Li Yongqi

Representative Bridges Constructed by China Railway Major Bridge Engineering Group

武汉长江大桥长江第一桥，中国现代化桥梁建设的代表

Wuhan Yangtze River Bridge, the fi rst bridge above the Yangtze River, and a representative of modern bridge construction in China

南京长江大桥建成时是世界最长的公铁两用桥

Nanjing Yangtze River Bridge, used to be the world’s longest double-deck road-rail truss bridge when it was completed

青岛海湾大桥世界上最长的跨海大桥，也是世界第二长桥

Jiaozhou Bay Bridge (or Qingdao Haiwan Bridge),the world’s longest cross-sea bridge and second longest roadway bridge

港珠澳大桥是世界最长的跨海大桥

Hong Kong-Zhuhai-Macau Bridge, would be the world’s longest sea bridge after it’s built

武汉杨泗港大桥世界跨度最大双层公路悬索桥

Wuhan Yangsigang Yangtze River Bridge, the world’s longest double-deck highway suspension bridge

镇江长江大桥世界跨度最长、荷载最大、设计速度最快的公铁两用悬索桥

Zhenjiang Yangtze River Bridge, the world’s longest road-rail suspension bridge with the maximum load and design speed

武汉鹦鹉洲长江大桥世界首座也是最大的主缆连续三塔四跨悬索桥

Wuhan Yingwuzhou Yangtze River Bridge, the world’s first and largest three-tower, four-span suspension bridge with consecutive main cables

武汉天兴洲大桥世界上第一座双塔三索面公路铁路两用斜拉桥；荣获国际桥梁大会“乔治·理查德森大奖”Wuhan Tianxingzhou Yangtze River Bridge, the

Thus the forest was forever kept in darkness.

Nevertheless, they went on to excavate, remove the obstacles in their way, and make the caisson continue to sink.

Their sweat and hard work brought about impressive, good news: on May 23, 2016, the open caisson on the north bank(Hanyang) sank to the desired position; on August 12, 2016, the open caisson on the south bank(Wuchang) sank to its specified position; and on November 21,2017, the roof of the main tower on the North Bank (Hanyang) was successfully completed.

On that final day, the whole construction site was filled with excitement. It symbolized that the world’s most multifunctional bridge would begin its superstructure construction.

The Yangsigang Yangtze River Bridge has been a pioneering project in constructing a bridge with an open caisson foundation in a bed of hard plastic clay,providing precious references for building bridges with long spans like a cross-sea bridge in the future. It represents breakthroughs in the design of base structures for bridge construction. ♦

Note: Being built by China Railway Major Bridge Engineering Group, the Yangsigang Yangtze River Bridge is the tenth Yangtze River Bridge in Wuhan, with an overall distance of 4.13 kilometers.As a super project on the Yangtze,it will be the world’s most multifunctional bridge, with designs for motor ways, non-motorized vehicle lanes, pedestrian passageways, and sightseeing and leisure areas. The bridge is predicted to be completed and open to traffic in 2019.

中铁大桥局的世界之最

world’s first cable-stayed, road-rail bridge with two towers and three cable planes; awarded the George S. Richardson Medal at the 27th International Bridge Conference

沪通长江大桥世界上最大跨度的公铁两用斜拉桥Hutong (Shanghai-Nantong) Yangtze River Bridge,the world’s longest cable-stayed road-rail bridge

新白沙沱长江特大桥世界第一座双层重载铁路桥

New Baishatuo Yangtze River Railway Bridge, the world’s first double-deck and heavy-load railway bridge

南京大胜关大桥世界首座六线重载高速铁路大跨度桥梁

Nanjing Dashengguan Yangtze River Bridge, the world’s first large-span, six-lane, heavy-load, and high-speed railway bridge

嘉绍大桥世界上最长最宽的多塔斜拉桥

Jiashao Bridge, the world’s longest and broadest multi-tower cable-stayed bridge

平潭海峡公铁大桥世界最长跨海峡公铁两用大桥

Pingtan Strait Dual-purpose Bridge, the world’s longest cross-sea road-rail truss bridge

孟加拉帕德玛大桥孟加拉国的“梦想之桥”

Padma Bridge, the “Dream Bridge” of Bangladesh

基甘博尼大桥东非最大斜拉式跨海大桥