On 7 August 2020, after a year and 235 days of excavation, a CREG 15.03m-diameter slurry TBM broke through on China’s Shantou Su’ai Subsea Tunnel project.
The excavation will make one of two identical tubes, under Su’ai Bay, each with 14.5m external diameter and 3.05km-long.
The two three-lane road tunnels intends to amend connections between both sides of the city of Shantou, placed about 300km east-north-east of Hong Kong.
In terms of building, the project is considered as the top challenging project of its kind in China. The tunnel alignment along geology includes mainly muddy soil, mud, medium-coarse sand, granite and muddy sand. Subsequently, the TBM overcame several challenges and difficulties, comprising boring in a high-intensity earthquake zone, with shallow overburden, hard rock and other complex mixed-ground conditions.
Therefore, CREG has customized the TBM to feature an integrated accessible cutterhead, spherical main drive, ultra-high-pressure sustaining system and twin-circuit air pressure control.
Thanks to targeted devices, information management, diverse simulations and optimized cutters, the drive was exactly controlled throughout.
The TBM’s best performance turned out to be 25m per day, 150m per week and 460m per month.
Source: Tunnels and Tunneling