The first steel box girder of the Yuchu Expressway Lüzhujiang Bridge, the world’s longest single-tower suspension bridge, has been successfully erected.

Release time:

2021-11-23 15:05

Source:

At 11:58 on November 20, as the cable-stayed crane smoothly lowered the 114-ton steel box girder onto the support structure beside the tower, the first steel box girder of the Yuchu Expressway Lüzhijiang Bridge—the world’s largest single-tower suspension bridge designed by Guizhou Provincial Transportation Planning, Survey and Design Research Institute Co., Ltd.—was successfully installed.

The main span consists of a total of 61 steel box girder segments, all of which are fully welded and fabricated in the factory. At the site’s pre-assembly yard for steel girders, these segments are assembled into complete sections. The steel girders are erected using a 180-ton cable crane, with each segment being lifted individually from the mid-span toward both sides in a symmetrical manner. The steel box girder being lifted this time is the Yuxi bank-end girder, measuring 6.34 meters in length, 31.4 meters in width, and 3 meters in height. The elevation difference between the bridge deck and the valley floor at the lifting area reaches as much as 320 meters—a lifting height that remains relatively rare in China. The successful erection of the first steel box girder has laid a solid foundation for the timely opening to traffic of the Yuchu Expressway in 2022.

The bridge is located at the junction between Yimen County and Shuangbai County, spanning the Lüzhui River. It is a key control project on the Yuxi-Chuxiong Expressway. The bridge has a total length of 798 meters, with a four-lane, two-way roadway, and a design speed of 100 kilometers per hour.

The bridge spans a typical, deeply incised “V”-shaped canyon. The terrain features continuous, rolling mountain ranges with steep and rugged topography. The bridge deck is situated at an elevation 320 meters above the river surface, and also stands 320 meters above the summit on the Chuxiong side. On the Yuxi side, the average slope is about 40°, indicating a steep terrain; on the Chuxiong side, the average slope is approximately 75°, approaching sheer cliffs. Vegetation is poorly developed on both banks, with bedrock exposed. The bedrock consists primarily of dolomitic limestone and slate.

The steep, nearly sheer terrain of the Chuxiong bank necessitated a bridge design that differs from the conventional two-tower suspension bridge. Instead, this bridge adopts a single-tower suspension bridge structure with no tower on one side. The main cables pass through cable holes drilled into the cliff face and are anchored to tunnel-type anchorages within the mountain via roller-type composite cable saddles. The steel box girders connect directly to the tunnel, transitioning from a monolithic box section to a split-box configuration that extends seamlessly into the tunnel and rests atop the tunnel’s secondary lining. This design eliminates both the bridge tower and the side spans of the main cables on the Chuxiong bank, as well as any approach bridges or abutments. As a result, the volume of excavation and slope protection work required on the Chuxiong bank is significantly reduced, yielding substantial economic benefits. Moreover, the structural form blends perfectly with the surrounding environment, creating a visually stunning landscape.

The Yuchu Expressway is a critically important segment of the Guangkun Expressway and also a key component of Yunnan Province’s expressway network. The total length of the route is 190.597 kilometers. Upon completion of the project, Shuangbai County in Chuxiong Prefecture will finally have access to an expressway, enabling seamless connectivity among neighboring counties and towns. This will open up a fast-track pathway for local residents to increase their incomes and become prosperous, and will play a vital role in promoting tourism development and economic construction in the central Yunnan region.