Jiuwanxi Bridge

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Jiuwanxi Bridge
九畹溪大桥
Zigui, Hubei, China
515 feet high / 157 meters high
525 foot span / 160 meter span
1998


One the most beautiful arch bridges in the entire 3 gorges region of China, the Jiuwanxi bridge crosses the mouth of one of the larger tributaries in the region. When it was originally completed in 1998, the bright red span was 515 feet (157 mtrs) above the normal level of the Yangtze River. By late 2006, the elevation level of the 3 Gorges reservoir had risen to 133 meters, reducing the height of the bridge to just 275 feet (84 mtrs). When the 3 Gorges Dam is finally completed in 2009, the reservoir will reach its full height of 175 meters, leaving the road deck just 138 feet (42 mtrs) above the water.

The deep gorge required the 525 foot (160 meter) span of the bridge to be constructed using the stayed cantilever method whereby a tower is erected on either side of the gorge and cables temporarily radiate out from it to support individual sections of the arch until the two halves can be joined in the middle. More unique to the span are the two steel arch ribs. Initially hollow during construction, concrete was pumped inside of them from the foundations upward to the crown. First used by the Chinese in 1990, they have refined and improved the technique and now use it on the majority of their steel arch bridges. Depending on the length of the span and the width of the bridge, different styles of tubing are used. For Jiuwanxi, a vertical dumbbell configuration was adopted with two tubes closely connected. Other configurations have single tubes further apart, double dumbbells or a mix of a dumbbell and single tubes such as was done on the Beipanjiang railway bridge. Further variations include tight clusters of tubing known as “multiple contiguous”.



Jiuwanxi Bridge Elevation


中国的整个三峡库区有一座美丽的拱桥,九畹溪大桥就建在在长江的一条支流九畹溪汇入长江的河口处。当它在1998年建成之时,通红的拱桥在当时的常水位之上157米。2006年后,三峡库区水位上升到了133米,也就把这座桥的高度降到了84米。当2009年三峡大坝全部建成,水库的水位就达到满水位175米高,这样,九畹溪大桥的桥面仅仅就只在水面之上42米高了。

深谷的存在,要求采用固定缆索平衡施工方法来架设一座160米跨度的大桥,该方法首先要在河谷两侧的山坡上建立龙门塔架,之后架设临时性的索道,用来吊装架设拱圈的拼装阶段,直至两半拱圈在中间部位合拢。更为独特的就是这两道钢管。在起初施工时空心的钢管中,混凝土从钢管底部向上泵送至拱顶位置。20世纪90年代首先由中国工程师使用,该方法被不断的优化改进,现在中国大多数的钢管拱桥上都有使用。依据桥梁的跨度和宽度不同,不同构造的钢管形式被采用。对九畹溪大桥而言,由两肢钢管紧密连接形成竖向哑铃型钢管拱圈。其他的构造形式,有分离式单管,双哑铃式,单管形式诸如北盘江铁路桥。更多的构造形式,还有诸如紧促的钢管束(组合式钢管)。


Image by Eric Sakowski / HighestBridges.com


Image by Eric Sakowski / HighestBridges.com


Jiuwanxi Bridge image taken before the 3 Gorges reservoir level had risen.


Image by Eric Sakowski / HighestBridges.com


Image by Eric Sakowski / HighestBridges.com


Image by Eric Sakowski / HighestBridges.com


Image by Eric Sakowski / HighestBridges.com


Image by Eric Sakowski / HighestBridges.com


Image by Eric Sakowski / HighestBridges.com




Jiuwanxi Bridge satellite image.

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