On January 10, the left line of Guangzhou Metro from Luogang Station to Shuixi Station was successfully connected. The subway section is a part to the second-phase project of the Guangzhou Metro Line 7 constructed by China Railway Tunnel Group, and is the first tunnel drilled by China’s first tunnel boring machine (TBM) integrating models of slurry-type shield tunneling, earth pressure balance tunneling and TBM tunneling.

　　The total length of the second phase project of Guangzhou Metro Line 7 is around 5.7 kilometers, and the section drilled by the integrated TBM measures is 1,086 meters long. The line crosses through multiple complex strata including full cross-section hard rocks, soft soil layers, upper-soft lower-hard strata and undiscovered boulders, which posed the biggest challenge for the construction team.

　　To solve the problem, the China Railway Tunnel Group worked with Guangzhou Metro Group, China Railway Engineering Equipment Group and China Railway Huasui Heavy Equipment Group to develop the world’s first three-model TBM targeting the complex engineering situation. Based on the dual-model TBM, the development team enhanced the drilling structure, increased the stiffness of the cutter and improved the machine’s anti-skid capability.

　　While all property rights of the integrated TBM belong to China, part of the technology takes the lead in the world. The machine integrates models of slurry-type shield tunneling, earth pressure balance tunneling and TBM tunneling. The three models can be flexibly shifted during the drilling process, which avoids the risks of long-time operation and the open-cut drilling in tunnels.