The super-large and super-heavy cutter head of the shield tunneling machine Zhenxing, which will be used to drill the Mangzhou Tunnel in the Guangdong-Macao In-Depth Cooperation Zone in Hengqin, was successfully lowered into a working well on June 6 to prepare for further installation and debugging.

The 510-metric-ton cutter head is 15.01 m (16.42 yd) in diameter. A workshop was built to ensure that welding of the cutter head would not be affected by the weather. In addition, different techniques were applied during the whole process, making it possible to finish welding in 30 days.

Cutter head of shield tunneling machine Zhenxing is successfully lowered into a working well on June 6 [Photo courtesy Zhuhai Daily]

Peng Yuandong, executive project manager, said that the first component of the shield tunneling machine was successfully lowered into a well on May 24 and that it only took nine days to complete the installation, which was much faster than the average speed of installation for machines of the same type. However, the lowering of the cutter head was the most difficult and dangerous part of the hoisting work. 

The two-way six-lane Mangzhou Tunnel project, undertaken by China Railway 15th Bureau Group, is a key project in Hengqin. Connecting the northwest tip of Hengqin Island and Hongwan area, it is expected to further improve the transportation network in the Cooperation Zone. 

The tunnel goes all the way across a super soft soil layer. The future drilling will face difficulties including the smallest burial depth and softest soil layer in China, super steep slope degree, and drilling under national first-level shipping routes.

The left line of the tunnel is 1,995 m (2,182 yd) in length with a shield section of 945 m (1,033 yd), while the shield section of the 2,032.15-m (2222.4-yd) right line is 978.31 m (1,069.89 yd). The entire project is expected to be completed and opened to traffic in 2024.