Special Focus

A Bridge that Connects the Mountains with the Plain 一桥连起山区和平原

- By Zhou Li

5 kilometers (about 3 miles) upstream of the ancient battlefiel­d of the Three Kingdoms in Chibi, Xianning City, Hubei, the Chibi Yangtze Highway Bridge in all its grandeur spans across the Yangtze River, with its closure completed on March 16, 2021.

After the bridge completes its constructi­on and opens to traffic, it will become an important passageway across the Wuhan City Circle and the Yangtze River Economic Belt. It will enable smooth traverse from the Mufu mountainou­s area across Hunan, Hubei, and Jiangxi to the Jianghan Plain, expediting the social and economic developmen­t of the area and promoting the developmen­t of the Yangtze River Economic Belt with “infrastruc­tural support” in Hubei transporta­tion.

Half a century of hopes pinned on a single bridge

Chibi, a city with a thousand years of history, is where the famous Battle of Red Cliff took place in the Three Kingdoms Period (220-280). Today, the charred remains of Chibi are still freshly smoldering the collective consciousn­ess of the people of the region.

The Yangtze River meanders for thousands of miles and nourishes the lush and lavish land of Chibi, but it also obstructs travel and economic developmen­t on both sides of the river. Xianning, which is home to 80 miles of Yangtze River shoreline, does not have a single bridge connecting the two shores. It is the only prefecture-level city along the river in Hubei Province that is impossible to cross without a boat. The constructi­on of this bridge linking both sides of the river is long-anticipate­d by residents.

In 2014, the State Council approved the Comprehens­ive Plan for the Transporta­tion Corridor of the Yangtze River Economic Belt, and the Jiayu and Chibi Yangtze River Bridges were both included in the key projects of the newly-built Yangtze River main line. The Hubei Communicat­ions Investment Group Co., Ltd. volunteere­d to invest in the constructi­on, and the dream of a bridge connecting Xianning had finally come true.

On March 21, 2018, the sound of rumbling along the vast expanse of the Yangtze broke the calm serenity of the ancient battlefiel­d that hearkens back to ancient clashes that took place more than 1800 years prior. The Chibi Yangtze Highway Bridge project officially broke ground that day. The dream of the Chibi Bridge that the people of Xianning had held so near and dear to their hearts for half a century had been made manifest.

Homegrown technology has made for a worldclass bridge

With a main span of 720 meters (2,400 feet), the Chibi Yangtze Highway Bridge is the world’s longest steel-concrete composite cable-stayed bridge in terms of span length. Experts believe that a breakthrou­gh has been achieved in the main span of this bridge type, which has been effectivel­y elongated from 1,900 to 2,400 feet with the closure of the Chibi Yangtze Highway Bridge. This has greatly enhanced the developmen­t of bridge-building technology and provides Chinese design and constructi­on solutions for bridges all across the world.

The geological conditions at the bridge constructi­on site are highly convoluted. The foundation is located on a limestone bedrock, from which karst caves are formed, the biggest of these is 51 feet. There are often water leakage and collapses during constructi­on. The nature of the rock strata is poor, making it difficult to drill the foundation.

Despite the difficulti­es, the installati­on of steel-concrete composite beams goes on as planned. The “framework” of the entire bridge is composed of 121 main steel-concrete beams. Each main steel-concrete composite girder includes two box-type

main girders, three cross girders, one longitudin­al girder and a concrete main bridge deck. Each composite girder weighs more than 500 tonnes and involves a host of complicate­d processes, and also requires installati­on with cable stays that interlock to 3-mm accuracy between each massive beam.

As the main stressed structure of the bridge, the installati­on of the stay cables is an important part of the constructi­on. The Chibi Yangtze Highway Bridge has a total of 116 sets of 232 stay cables, with steel wire strength reaching 1860 MPa. The longest single-stay cable is 1,270 feet and the maximum weight is 38.49 tonnes. The “needlework” that fastens the cables is not easy, as the stayed cable weighs more than ten tonnes, and has 253 steel wires tied inside. The “needle” itself is a large crane that “sews” from the 730-foot-high main pylon. Workers use a tension anchor rod and crane to hoist the coiled stay cables to their soaring heights and fix the cable head to the main pylon. The other end of the cable is on the bridge deck, and it is towed by more than 10 pulleys. With the crane working in complete concert with the workmen below, the cables are inserted one by one into the anchor pipe. Workers “thread” nonstop for three hours to get each cable through.

The organizati­on responsibl­e for the constructi­on is China Railway Bridge Bureau, a worldleadi­ng bridge constructi­on group. The team has been bolstering its technical research and as a result, made a number of important technical innovation­s. On the Chibi Yangtze Highway Bridge, the installati­on time of the two main beams was 12 days, four days shorter than with existing technology. Meanwhile, the time

taken to lift one beam was shortened by three hours, giving rise to something now affectiona­tely called, “Chibi Bridge Speed.”

The main pylon of the bridge was formed into an H shape, the north pylon is 710 feet high, and the south pylon is 730 feet high. The innovation­s in design and technology for this project have achieved a laundry list of world firsts, and have overcome problems that have plagued bridge builders the world over, i.e., large-volume pile cap concrete pouring, superhigh main pylon one-time vertical concrete transferen­ce, cable force of large-span 2,400-foot steel-concrete composite beams, and bridge linear control. (Translatio­n: Chase Coulson)

 ??  ?? Profile of the bridge prior to its completion­合龙前的大桥一侧
Profile of the bridge prior to its completion­合龙前的大桥一侧
 ??  ?? The bridge being outfitted with box girders建设中­的赤壁长江公路大桥正­在调装箱梁
The bridge being outfitted with box girders建设中­的赤壁长江公路大桥正­在调装箱梁
 ??  ?? The completion of Chibi Yangtze Highway Bridge赤壁长江­公路大桥合龙现场
The completion of Chibi Yangtze Highway Bridge赤壁长江­公路大桥合龙现场
 ??  ?? The constructi­on site in full swing施工现场热­火朝天
The constructi­on site in full swing施工现场热­火朝天

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