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.

楊泗港大橋一號主塔封頂 攝影/張衛(wèi)東No.1 main tower of the Yangsigang Yangtze River Bridge sealed roof Photo by Zhang Weidong

2017年11月21日7時28分，隨著建設者們將最后一方混凝土澆筑完畢，武漢楊泗港長江大橋漢陽岸主塔成功封頂。一時間，人人歡呼雀躍，熱鬧非凡。

對岸，80后小伙子李永旗隔江遙望這座高231.9米、相當于80多層樓高的主塔，心潮澎湃。一個月后，他負責的南岸主塔也將如期封頂。

作為楊泗港大橋第二項目部經(jīng)理，李永旗看著屹立于江中的雄偉“巨人”，思緒回到一年前。

2016年8月12日。每當提起那一天，李永旗都異常興奮：“簡直就像做夢一樣。”

就在前一天下午，他檢查楊泗港大橋南岸（武昌）沉井下沉情況。“理論上來說，沉井平均一天下沉20厘米，但有時候會一連半個月紋絲不動，這是最讓人煎熬和焦慮的?！倍辆疀]有下沉的跡象，他有點失望地離開。

沒想到第二天天剛亮，他的手機便響個不停：“楊泗港大橋武昌南岸主塔沉井下沉到位?！笔盏较灿?，工地所有人奔走相告，橋梁界的老專家也不辭辛苦趕來，只為親睹這一刻。

這突如其來的驚喜，讓李永旗激動萬分。他乘興作詩一首：

一百五十日與夜，

數(shù)名弟兄汗和血。

十二萬噸駐江底，

承載百年做根基。

2014年12月3日，作為武漢市第十座長江大橋，楊泗港長江大橋破土動工。為了不影響長江航道通行，橋在江中基本不設橋墩，采用“一跨過江”形式，跨度1700米。楊泗港大橋由此成為世界上跨度最大的雙層懸索橋。

欲戴其冠，必承其重。作為世界之最，大橋在施工中遇到各種難題。

由于跨度大、車道多，作為“挑夫”的大橋南、北兩座主塔必將承受更大的壓力。建設者們將塔墩設計為橢圓形沉井基礎，平面面積相當于8個籃球場的大小。

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

北岸主塔離長江大堤僅數(shù)米距離，這樣一個“巨無霸”在下沉過程中一旦對大堤產(chǎn)生影響，極易引起大堤下沉、開裂，甚至潰堤。

楊泗港大橋第一項目部總工程師黃峰、項目經(jīng)理韋正平，第二項目部經(jīng)理李永旗等人聯(lián)合橋梁專家們一起，探討摸索，首創(chuàng)“C”字形排樁防護結構，在沉井與大堤間構筑一道防護墻，可將大堤防護樁在施工中的變形控制在厘米級，從而最大程度保障大堤和沉井周圍建筑的安全。這一“江河臨邊施工防護方法”，獲得國家發(fā)明專利。

大堤安全問題解決，還有更硬的骨頭等著他們。大橋的南北兩岸塔址處地質(zhì)均為硬塑黏土層。這種土質(zhì)硬如巖石，又比巖石有可塑性，無法采用爆破等常規(guī)方式。但凡遇到此類地質(zhì)基礎，設計者們都忍痛改變選址方案。而這里的黏土深達6.2米左右，堪稱世界之最。

施工人員使出渾身解數(shù)，空氣吸泥、水下爆破、高壓射水、空氣幕等等全用上，試圖保證沉井的順利下沉。最后，他們研發(fā)出射水壓力是普通吸泥機25倍的多功能吸泥機，終于讓堅硬的黏土變松、變散，讓深井得以緩緩下沉。

即使有先進的工藝和設備，施工過程也不順利。2號沉井下沉僅一兩米不久，便被迫停止。蛙人下水摸查發(fā)現(xiàn)，地下有大量古樹沉積，給深井下沉造成障礙。

江底怎會有古樹？數(shù)量有多少？李永旗在圖書館連泡一個多星期，通過查找大量文獻、地方志，終于得知，這里曾是一片樹林，公元1700年間，由于長江改道，這片樹林被淹沒到江底，從此不見天日。

挖掘、清障、繼續(xù)下沉……任何困難都阻擋不了工程安全順利完成的決心。

他們的攻堅的汗水終于換來驕人的喜訊——

2016年5月23日，北岸（漢陽）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（漢陽）主塔成功封頂……整個工地沸騰了。它標志著這座世界上功能最全的大橋，拉開上部結構施工的序幕。

楊泗港大橋開創(chuàng)在硬塑黏土層建設沉井基礎橋梁先河，為將來建設跨海大橋等大跨度橋梁提供寶貴借鑒，實現(xiàn)橋梁建設基礎結構設計上的新突破。?

楊泗港大橋建筑工地上，中鐵大橋局打出口號“打造世界一流建橋國家隊” 攝影/許溶豐“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

小貼士：武漢楊泗港長江大橋由中鐵大橋局施工建設，是武漢市第10座長江大橋，全長4.13公里。作為長江主軸上的超級工程，楊泗港長江大橋?qū)⑹鞘澜缟瞎δ茏钊拇髽颍C動車道、非機動車道、人行道及人行觀光休息區(qū)等多種功能設置。該橋預計2019年建成通車。

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.

從南岸江底挖掘出的古樹 攝影/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

武漢長江大橋 長江第一橋，中國現(xiàn)代化橋梁建設的代表

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

南京長江大橋 建成時是世界最長的公鐵兩用橋

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

青島海灣大橋 世界上最長的跨海大橋，也是世界第二長橋

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

港珠澳大橋 是世界最長的跨海大橋

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

武漢楊泗港大橋 世界跨度最大雙層公路懸索橋

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

鎮(zhèn)江長江大橋 世界跨度最長、荷載最大、設計速度最快的公鐵兩用懸索橋

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

武漢鸚鵡洲長江大橋 世界首座也是最大的主纜連續(xù)三塔四跨懸索橋

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

武漢天興洲大橋 世界上第一座雙塔三索面公路鐵路兩用斜拉橋；榮獲國際橋梁大會“喬治·理查德森大獎”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.

中鐵大橋局的世界之最

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

滬通長江大橋 世界上最大跨度的公鐵兩用斜拉橋Hutong (Shanghai-Nantong) Yangtze River Bridge,the world’s longest cable-stayed road-rail bridge

新白沙沱長江特大橋 世界第一座雙層重載鐵路橋

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

南京大勝關大橋 世界首座六線重載高速鐵路大跨度橋梁

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

嘉紹大橋 世界上最長最寬的多塔斜拉橋

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

平潭海峽公鐵大橋 世界最長跨海峽公鐵兩用大橋

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

孟加拉帕德瑪大橋 孟加拉國的“夢想之橋”

Padma Bridge, the “Dream Bridge” of Bangladesh

基甘博尼大橋 東非最大斜拉式跨海大橋

Kigamboni Bridge, the largest cable-stayed crosssea bridge in East Africa

摩洛哥穆罕默德六世大橋 非洲最大斜拉橋

Mohammed VI Bridge, the largest cable-stayed bridge in Africa

敢叫天塹變通途

文/劉冬莉 譯/劉潔