On June 30, with the last blast, the Gexi Tunnel of the Xuancheng-Jixi High-Speed Railway, constructed by China Railway 14th Bureau Group, was successfully holed through. This marks major progress in the construction of China's in-city high-speed railway with the highest bridge-tunnel ratio under construction, laying a solid foundation for the next stage of ballastless track construction and line opening.

All 24 tunnels holed through

The Gexi Tunnel is located in Jixi County, Xuancheng City, Anhui Province, with a total length of 2,801 meters. The tunnel's geological conditions are complex; the entrance is less than 10 meters from the county road, the mountain is steep with exposed bedrock, and the exit features steep terrain and a narrow construction site, making tunnel entry difficult. During construction, the builders specially added an auxiliary adit for construction, effectively overcoming the difficulty of tunnel entry.

The Xuancheng-Jixi Railway pre-station Section 3, constructed by China Railway 14th Bureau Group, has a line length of 30.98 kilometers. The construction content includes 35 bridges and 24 tunnels, with a total bridge-tunnel length of 29.64 kilometers, accounting for 95.7% of the line length. It is the section with the largest number of double-track tunnels in a single pre-station section, the highest bridge-tunnel ratio, the most and most complex serial connections of tunnel and bridge portals, and the largest number of tunnels over 2 kilometers in the entire Xuancheng-Jixi High-Speed Railway, and also the section with the highest bridge-tunnel ratio on the whole line.

Facing construction challenges, the project team planned in detail and continuously optimized the scheme, comprehensively using TSP, 3D imaging advanced forecasting and other technological means to predict geology, strengthening the digitalization of tunnel construction, and effectively overcoming construction difficulties. At the same time, addressing the ultra-high bridge-tunnel ratio, the project vigorously carried out technical research and developed multiple tunnel construction patents, including a monitoring device for the effect of grouting with formwork at the tunnel lining crown, providing a useful reference for in-city high-speed railway tunnel construction under complex geological conditions in China.

"Improve efficiency, ensure milestones, safeguard safety  create quality intensive 120-day campaign" labor competition

The project team carried out the labor competition in depth. Since entering the site, they have successively completed major engineering milestones, including the first tunnel holing-through on the whole line, taking the lead in completing all continuous beam construction, and taking the lead in opening the girder erection channel. With the successful holing-through of the Gexi Tunnel, all 24 tunnels in the section have been holed through, and the project's pile foundations, pile caps, pier shafts, continuous beams, and cast-in-place girder construction have all been completed.

The Xuancheng-Jixi High-Speed Railway is located in Xuancheng City, Anhui Province. It is the first in-city high-speed railway in Anhui Province and an important component of the Jiangsu-Anhui-Jiangxi rapid railway corridor and the intercity railway network in the Wanjiang region. The main line has a total length of 111.7 kilometers and a design speed of 350 kilometers per hour. After opening to traffic, it will help improve the regional road network layout, shorten distances between Jiangsu, Anhui, Jiangxi and other places, and is of great significance for promoting the construction of the Southern Anhui International Cultural Tourism Demonstration Zone and promoting coordinated regional economic development.