On July 27, China Construction Sixth Engineering Division Corporation Ltd. completed the hoisting operation of the last steel box girder on the southern navigation bridge of the Zhoushan-Daishan Cross-Sea Bridge. The closure of the arch bridge marked a key step towards the final completion of the Zhoushan-Daishan Cross-Sea Bridge, which is the first ever deep-sea bridge project conducted by China State Construction Engineering Corporation (CSCEC).

Precise closure

As a massive cross-sea project, the Ningbo Zhoushan Port Main Channel is a major strategic project connecting the 21st Century Maritime Silk Road. Constructed by CSCEC, the Zhoushan-Daishan Cross-Sea Bridge No. 2 contract has a total length of 9.51 kilometers, including 5.35 kilometers of main road and 4.17 kilometers of oversea interchange ramp.

The southern navigation bridge is a deep-sea double-tower entire steel box girder cable-stayed bridge with a total span of 750 meters, and its main span has a length of 390 meters. The bridge has 55 beam segments, and the No. 2 contract constructed by CSCEC has 28 beam sections, of which 21 beam segments need to be cantilevered using bridge deck cranes.

During the closing of the southern navigation bridge, a 340-metric-ton adjustable bridge deck crane was deployed to perform the hoisting operation. The construction team also adopted the temperature closure control technology to minimize the effects of temperature changes, facilitating the smooth and accurate closure of the bridge.

In order to ensure the construction process, the deck and beams of the bridge were assembled in advance at the project headquarter, transported to the construction site by a 600-metric-ton flat barge, and hoisted in place by a 1,200-metric-ton floating crane. The project department conducted a finite element analysis to accurately simulate the hoisting operation, seized the perfect timing for construction, and completed the hoisting task successfully, paving the way for the large-scale construction of the steel box girder.

Overcoming obstacles

In the past three years since the start of construction, the project department has successfully dealt with typhoon 14 times, and properly taken COVID-19 prevention and control measures to ensure resumption of work at the construction site. The project team has completed 92% of the contract when only 80% of the construction period has passed. The successful closure of the southern navigation bridge before the annual typhoon season marked a significant progress for the whole project.

Scientific innovation

With the longest steel pipe measuring 109 meters in length and 2 meters in diameter, the southern non-navigation bridge steel-pipe pile foundation has set a new world record in the construction of a cross-sea bridge project.

Changbai Interchange featured extreme technical difficulties in the assembly process, and its completion has set new standards for offshore interchange projects in China. The project team has overcome a series of key technical problems during the construction process.

The construction technology featuring a detachable bottom plate of the steel box girder was a breakthrough in the field of cross-sea bridge construction. Applying the first multi-directional adjustable steel box girder and the first protective tube supporting offshore steel platform in the construction process, CSCEC has demonstrated its excellent technical strength in bridge construction.

The project’s application of the BIM technology in the construction of the bridge was named a finalist of the Global Annual Awards for Infrastructure Projects. Also, the project department has compiled the “Quality Control Reference Manual,” a construction site code of conduct guidebook later promoted by the company headquarters across the board, while a safety experience center has been established as CSCEC’s first standard field laboratory.

As a groundbreaking project of CSCEC’s expansion from onshore bridge projects to offshore ones, the Zhoushan-Daishan Cross-Sea Bridge project marks a new chapter in CSCEC’s history of bridge construction.