On April 17, with the completion of the jacking of the 69th ring pipe section on the left line of the pipe-jacking interval, the three-lane extra-large cross-section rectangular pipe-jacking tunnel of the Guangzhou Nansha Phoenix Avenue Project successfully overcame technical challenges and safely passed beneath the Guanfo Expressway viaduct.

Construction site of the underpass project

The pipe-jacking section of the Fengze Road-Huangge South Road Tunnel of the Phoenix Avenue Rapid Reconstruction Project passes beneath Huangge South Road and the Guanfo Expressway viaduct. The pipe-jacking section is about 151.5 meters long, with a cross-section of 14.8 m × 9.426 m, making it currently the **largest rectangular pipe-jacking cross-section in South China. The buried depth of the interval is 4.07 m to 4.86 m, and the edge line of the pipe jacking is only about 2 meters away from the pile foundation of the existing Guanfo Expressway viaduct, resulting in high construction difficulty and high construction risk.

Actual view of the underpass project

In response to the key construction difficulties such as the extra-large cross-section, ultra-shallow cover, and proximity to bridge pile foundations, and to ensure the safe and smooth jacking of the pipe-jacking machine beneath the Guanfo Expressway viaduct, the Nansha District Construction Center organized the project department to take multiple measures: it repeatedly organized in-depth discussions among project participating units and the expressway ownership unit, continuously optimized the bridge protection plan, and repeatedly invited industry experts to demonstrate and conduct on-site acceptance of the construction plan; it introduced automated monitoring to grasp the bridge's dynamics in real time, providing a solid safety guarantee for construction, and ultimately achieving the goal of safely passing the pipe-jacking section beneath the Guanfo Expressway viaduct.

The successful underpass of the Guanfo Expressway viaduct by this tunnel pipe-jacking section fills the technical gap for extra-large cross-section pipe jacking beneath major structures. It not only provides valuable experience for subsequent pipe-jacking construction, but also lays a solid foundation for ensuring the important milestone of full-line breakthrough.