On the morning of the 5th, at the launching shaft of the Tianxiang Avenue Tunnel of the newly built Nanchang-Jiujiang High-Speed Railway, located in the High-Tech Development Zone of Nanchang City, Jiangxi Province, the cutterhead of the "Hero" shield tunneling machine began to rotate slowly, and the Tianxiang Avenue Tunnel, constructed and managed by the Changjiu Intercity Railway Company and built by the China Railway 14th Bureau Group, commenced tunneling. This marks the official launch of the shield tunneling machine with the largest diameter for high-speed railway tunnels in China.

The shield tunneling machine with the largest diameter for high-speed railway tunnels in China has started excavation in Nanchang, Jiangxi.

The newly built Nanchang-Jiujiang High-Speed Railway is located in the central and northern part of Jiangxi Province and is a key section of the Beijing-Hong Kong (Taiwan) Corridor, one of the "Eight Vertical and Eight Horizontal" main high-speed railway corridors in the National Medium- and Long-Term Railway Network Plan. The line starts from Lushan Station on the Anqing-Jiujiang High-Speed Railway and runs south to Nanchang East Station on the Nanchang-Ganzhou High-Speed Railway, with a total length of 137.7 kilometers, a design speed of 350 kilometers per hour, and is expected to be completed and opened to traffic in 2027.

The 6.379-kilometer-long Tianxiang Avenue Tunnel is a controlling project of the entire Nanchang-Jiujiang High-Speed Railway line. It is a single-tube double-track tunnel, of which the shield-tunneled section is 4.4 kilometers long and is excavated using a 14.8-meter-diameter slurry balance shield tunneling machine, the largest-diameter shield tunneling machine for high-speed railway tunnels in China and the first large-diameter shield tunnel in Jiangxi Province. The internal structure of the tunnel adopts an integral fully precast box culvert, the first implementation of its kind in a 350-kilometer-per-hour high-speed railway tunnel in China.

Aerial view of the shield tunneling machine with the largest diameter for high-speed railway tunnels in China.

Xia Xiaoren, commander of the Changjiu Command of the Changjiu Intercity Railway Company, told reporters that the Tianxiang Avenue Tunnel is one of the high-speed railway shield tunnels with the most complex construction environment and geological conditions to be crossed in China today. The shield tunneling machine will traverse composite strata such as water-rich sand layers and argillaceous sandstone over long distances, and will successively cross 78 risk sources including Nanchang Metro Line 1 and the Yangmen Village shantytown. It will withstand a maximum water pressure of 6 bar (equivalent to the pressure at a water depth of 60 meters). The overburden thickness at the launching point of the shield-tunneled section is 9.5 meters, and that at the receiving (exit) point is only 9 meters. The project is characterized by a large excavation cross-section, a long tunnel interval, and numerous geological risks.

In response to the major and difficult points of the project, the project team conducted targeted research and design on the cutterhead structure, cutter types, drive seals, pressure resistance, and corrosion resistance, and tailor-made the "Hero" shield tunneling machine. The machine has a total length of 134 meters and weighs about 3,700 tons, and adopts a number of innovative technologies such as a cutterhead hydraulic wear detection device.

The photo shows preparations for the launch and excavation of the shield tunneling machine with the largest diameter for high-speed railway tunnels in China.

"We will rely on digital shield tunneling and integrate artificial intelligence algorithms to explore an autonomous tunneling mode for the shield tunneling machine for the first time, realizing the functions of 'manned monitoring, unmanned driving, and automatic deviation correction' for the shield," said Wang Xing, shield project manager of the China Railway 14th Bureau. "We will also give full play to the advantages of our core large-diameter shield tunneling technology and rich construction experience, and use innovative technical means such as shield big-data visualization and monitoring and early warning to ensure safe construction and quality compliance."

After the Nanchang-Jiujiang High-Speed Railway is completed and opened to traffic, it will be of great significance for Jiangxi Province to build an integrated comprehensive transportation system for Nanchang-Jiujiang integration, further connect with and integrate into the Guangdong-Hong Kong-Macao Greater Bay Area, support the implementation of the Yangtze River Economic Belt development strategy, and promote the high-quality economic and social development of areas along the line. By then, the Beijing-Hong Kong High-Speed Railway corridor will be fully connected, and a full high-speed rail journey from Beijing via Hefei and Nanchang to Shenzhen (Hong Kong) will be realized.