China's domestically produced 14-meter diameter shield tunneling machine, "Fenjihao", rolled off the production line at Tongzhou Bay in Nantong, Jiangsu province, on March 31. It will be used for the construction of the Yancheng-Yixing High-speed Railway Yangtze River Tunnel project.

The "Fenjihao" shield tunneling machine is completed at Tongzhou Bay in Nantong, Jiangsu province, on March 31. [Photo/Nantong Daily]

The machine is 145 m long and weighs about 3,800 metric tons. It comes with smart features that allow for remote operation, real-time monitoring, and automatic assembly of tunnel segments. This means the tunnel's main structure and interior can be built in just one go.

The Yancheng-Yixing High-speed Railway Yangtze River Tunnel project runs a length of 8,130 m, connecting Jingjiang in the north with Jiangyin in the south. The shield machine will excavate 6,710 m continuously, a long journey through soft soil, high water pressure, sand layers, uneven rock, and even gas-bearing ground.

This tunnel is China's first high-speed rail shield tunnel to use socket-type segments, a design inspired by the ancient mortise-and-tenon technique used in Chinese woodworking. The segments can fit tightly together, and the machine's intelligent system will help assemble them with high precision.

After rolling off the line, "Fenjihao" will be disassembled, transported to the construction site, reassembled, and tested — before beginning its journey beneath the Yangtze River.