Completion of Pier No. 9, a Concrete-Filled Steel Tube Lattice Pier of Nanxi River Grand Bridge on the China-Vietnam Railway (Wenshan-Mengzi Railway)

en.Wedoany.com Reported - On November 12, construction of Pier No. 9, a concrete-filled steel tube lattice pier of the Nanxi River Grand Bridge on the Wenshan-Mengzi Railway in Yunnan, was completed, with the final lift-up operation of concrete-filled steel tube pouring finished. This structure is the first lattice pier of its kind adopted in a domestic railway project. The pier is assembled from a combination of steel tubes and I-beams, with high-strength concrete poured inside, and is mainly used for high-pier bridge construction in mountainous areas.

The Nanxi River Grand Bridge has a total length of 789.71 meters and is the tallest bridge on the entire Wenshan-Mengzi Railway, with a maximum height difference of 118 meters between the bridge deck and the ground. The bridge is located in mountainous terrain with complex conditions, and the construction of high-pier structures places high demands on component installation precision, overall stability, and on-site work organization. The lattice pier adopted this time forms a trapezoidal structure, wide at the bottom and narrow at the top, through a combination of steel tubes and I-beams, with high-strength concrete poured inside so that the steel components and concrete jointly bear the load.

Compared with traditional solid concrete piers, the lattice structure reduces the amount of concrete used inside the pier body and forms a load-bearing system through the combination of steel components. According to project disclosures, this structure can save 30% to 50% of concrete and steel. The construction adopts a prefabricated component assembly method, reducing the amount of large-volume concrete work on site and also helping to control operational risks and on-site environmental impact during high-pier construction.

The concrete-filled steel tube composite form can leverage the respective material properties of steel and concrete and improve the overall mechanical performance of the pier. The lattice pier body has good structural stiffness and seismic performance, and is adaptable to bridge foundation and pier body design under complex mountainous terrain conditions. The completion of this construction provides an engineering practice case for the application of this type of structure in railway high-pier bridges.

The Wenshan-Mengzi Railway is located in southeastern Yunnan Province and connects Wenshan Zhuang and Miao Autonomous Prefecture with Honghe Hani and Yi Autonomous Prefecture. The line has a total length of approximately 116 kilometers, a design speed of 160 kilometers per hour, and adopts the National Railway Class I double-track mixed passenger and freight electrified standard. According to project construction data, the exact length of the line is 114.608 kilometers, including 101.953 kilometers of newly built line and 12.655 kilometers of the second track added to the existing Yuhe Railway.

As of November 12, the pre-station works of the Wenshan-Mengzi Railway were approximately 63% complete overall, and works including bridges, tunnels, and station buildings are still underway. After the completion of Pier No. 9 lattice pier of the Nanxi River Grand Bridge, subsequent construction of the related bridge will continue around the main structure and supporting works.