On September 25, after more than six years of intensive work, the large-chainage section of the downhill line of the 21–22# working shaft mined tunnel (mining method) on the Guangzhou–Foshan East Ring Line, constructed by China Railway 14th Bureau Group, was holed through. With this, the entire mined tunnel section of the Guangzhou–Foshan East Ring Line has been fully connected, laying a solid foundation for track laying on the line on schedule.

Large-chainage holing-through of the downhill line of the 21–22# working shaft mined tunnel

The tunnel holed through this time is a double-tube, single-track tunnel, with each tube 3,270 meters long. The tunnel has high humidity and poor ventilation, and the average working temperature is often above 40 degrees Celsius. In particular, all material access and ventilation must be carried out through one inclined auxiliary shaft and one vertical shaft. In addition, the tunnel is located in a mountainous belt where the surrounding rock properties vary greatly; these inherent constraints have brought enormous challenges to construction organization and support.

21# vertical shaft

To ensure safe and smooth holing-through of the tunnel, the project used advanced scientific detection methods such as ground-penetrating radar and advanced horizontal drilling to dynamically optimize construction techniques. It adopted the "full-face + bench with temporary invert" excavation method and employed support measures including advanced long pipe roofs, small conduits, pre-grouting, and radial grouting, effectively stabilizing the working face, reducing safety risks for construction personnel, and achieving steady tunnel advancement.

Simulation emergency drill for collapse in the mined tunnel

During construction, the project vigorously pursued technological innovation. The self-propelled hydraulic invert trestle was used to achieve parallel operations, and an intelligent wet-spraying robotic arm was used in the initial support process, increasing construction efficiency by nearly half. An intelligent drainage system was also built to achieve uninterrupted drainage around the clock.

Self-propelled hydraulic invert trestle used for invert construction

It is reported that the Guangzhou–Foshan East Ring Line is a key line of Guangzhou's east–west transportation trunk network. Once completed, it will connect six intercity rail lines. At that time, it will take only half an hour from Guangzhou South Railway Station to Baiyun Airport, and only 20 minutes to Baiyun Airport, achieving seamless connection between high-speed rail and air travel.