en.Wedoany.com Reported - On May 20, the main bridge of the Beijiang Grand Bridge, a key control project of the Qingyuan Qing(xin) to Guangzhou Hua(du) Expressway, was successfully closed, becoming the largest four-tower, double-cable-plane, semi-floating system prestressed concrete girder cable-stayed bridge in China. With this, the main line of the Qinghua Expressway has achieved full connectivity, laying the foundation for its opening to traffic by the end of the year.

The main bridge of the Beijiang Grand Bridge has a total length of 1,440 meters with a main span of 360 meters. Inspired by the "Qingyuan Phoenix City," the tower crowns resemble "phoenix feathers," featuring an elegant shape and unique structure.

Located in an area with extremely strong karst development, secondary faults of the Beijiang Fault, and abrupt changes between soft and hard strata, the construction of this bridge was a tough battle against complex geological conditions.

"The karst development at the bridge site is extremely strong. The average length of the 120 pile foundations for the main piers exceeds 80 meters, with the longest reaching 102 meters. They had to penetrate multiple layers of beaded karst caves, where the slightest carelessness could cause hole collapse or water inrush," introduced Zhou Wei, Director of the Qinghua Expressway Management Office.

The project team implemented refined management through a "one pile, one plan" strategy and targeted karst cave pre-treatment plans, ensuring a 100% one-time hole completion qualification rate for the 120 main pier pile foundations, all of which were Class I piles.

The four main towers of the Beijiang Grand Bridge are all water towers. The nearly 150-meter-high "phoenix feather" type variable curvature cable towers posed extreme difficulty in alignment control, with construction significantly affected by strong winds, floods, and vessel navigation—equivalent to "embroidery" performed hundreds of meters in the air.

"The biggest difficulty in closure was the relatively wide bridge deck, reaching 37.6 meters. We used a mobile operation platform with 'cable-stayed hanging baskets' to cast the concrete section by section. At the same time, through BIM digital modeling, BeiDou positioning, and full-process stress-strain monitoring, we could monitor the bridge deck elevation and stay cable tension at any time, like installing a 'smart brain' on the bridge to ensure construction safety and quality," said Xu Lu, Project Manager of the TJ3 Section of the Qinghua Expressway for China Railway Major Bridge Engineering Group.

The precision of the mid-span closure directly affects the internal forces and alignment of the entire bridge. If the forces on both sides of the closure gap are unbalanced, it can easily lead to girder deflection and significant elevation deviations. The project team used iterative calculations based on on-site data to precisely apply balance counterweights, eliminating the elevation difference at the closure gap. In the 48 hours before closure, elevations were continuously monitored every 2 hours to dynamically adjust deviations. Ultimately, the mid-span closure elevation deviation was only 3 millimeters, and the relative elevation differences of the five closure segments were all less than 5 millimeters, far superior to the 20-millimeter specification requirement, ensuring structural safety and durability.

The Qinghua Expressway project is a vital corridor connecting Qingyuan and Guangzhou, serving as a significant support for promoting Guangzhou-Qingyuan integration and the development strategy of the Guangdong-Hong Kong-Macao Greater Bay Area. Once completed, the Qinghua Expressway is expected to shorten the travel time between Qingxin and Huadu by about 20 minutes compared to existing routes. By then, the auto parts industry cooperation between Huadu District and Qingxin District will be deeply linked through the expressway network, and industries such as agricultural product cold chain logistics, cultural tourism, and health and wellness will also usher in new development opportunities.

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