Unprecedented Deep Sea Maintenance Achieves Major Milestone in China’s Tunneling History
China has pushed the boundaries of underground construction technology with the successful completion of a critical maintenance operation deep beneath the sea. Focusing on the Jintang Undersea Tunnel, which is set to become the world’s longest underwater high-speed rail tunnel, engineers executed a complex and demanding maintenance task at an extraordinary depth, setting new national records and demonstrating cutting-edge innovations in tunnel technology.
Why This Maintenance Operation Is a Game-Changer
This operation involved inspecting and replacing a total of 104 cutterheads on the tunnel boring machine (TBM) named Yongzhou. Conducted under extreme conditions—at approximately 80 meters below sea level and under a formidable 7.8 bar of water pressure—the operation lasted 21 days. The success signifies a leap forward for China’s underground engineering capabilities, particularly in high-pressure, deep-sea environments where conventional maintenance often fall short.
The Depth That Redefines Limits: China Sets a New Record
The Jintang Tunnel, part of the crucial Ningbo-Zhoushan Railway project, extends over 16.18 kilometers. The maintenance took place at a depth where the water and soil pressure combined reach a staggering 8.5 bars. Such a level of sophistication in repair and inspection processes underscores China’s commitment to tackling depths and pressures that previously limited tunneling activities globally.
Specifically, the TBM “Yongzhou” encountered a challenging geological environment—mainly high-strength rocks reaching up to 191 megapascals (MPa) in resistance. Navigating a journey through such tough terrain requires highly specialized cutterheads capable of standing intense wear, which further enhanced the importance of this meticulous maintenance operation.
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