Recently, the cutterhead of the "Yongping" shield machine began to rotate slowly, and the entire machine advanced gradually... The shield construction of the Shantou Bay subsea tunnel on the Shantou-Shanwei Railway, a single-tube double-track high-speed rail subsea tunnel with a design speed of 350 km/h, has officially begun.

The Shantou-Shanwei Railway is under the general contracting of China Railway Design Corporation, an enterprise in the Tianjin Port Free Trade Zone. The Shantou Bay subsea tunnel is currently the world's largest-diameter high-speed rail subsea shield tunnel, with the excavation diameter of the shield cutterhead alone reaching 14.57 meters.

According to reports, the tunnel has a maximum burial depth of 67 meters and a maximum water depth of 10 meters. The shield passes through complex strata, including a 809-meter long full-face granite section, with rock strength up to 166 MPa and boulders up to 5 meters in diameter. The construction of the Shantou Bay subsea tunnel incorporates many world-class challenges, posing severe tests for the builders.

As the general contractor, China Railway Design Corporation organized the design department to carry out detailed design. To overcome the time constraints of in-tunnel assembly and ensure the smooth lifting of the shield machine, the project department and the tunnel professional team of the design department promptly and efficiently advanced the structural design optimization and calculation analysis of the second lifting shaft, ensuring the smooth launch of the shield machine.

In addition, regarding the shield machine itself, the project department has repeatedly invited domestic shield technology experts for discussions and customized the "Yongping" slurry balance shield machine. The cutterhead is capable of changing cutters under atmospheric pressure, equipped with a total of 303 cutters, with a minimum cutter spacing of 90 mm, and features a rolling detection system. These parameters all represent world-class levels. Meanwhile, the dismantling of the super-large-diameter shield machine in an undersea chamber is the first of its kind in China, with a single component weighing up to 220 tons.

The Shantou Bay subsea tunnel is located in Shantou Bay, Guangdong Province, and is a controlling project of the entire Shantou-Shanwei Railway. The tunnel has a total length of 9,191 meters, including 2,169 meters crossing the seabed of Shantou Bay. The smooth launch of the shield for the Shantou Bay subsea tunnel marks an important breakthrough in the construction of the Shantou-Shanwei Railway. Once completed, the project will effectively shorten the development distance between eastern Guangdong and the Pearl River Delta, provide support for the construction of the Guangdong-Hong Kong-Macao Greater Bay Area, and boost the economic takeoff of eastern Guangdong.