China’s First Homegrown Saturation Pressurized TBM Entry System “Deep-Sea Space Station” Makes Its Successful Debut

IT Home (Feb 8) reports that at the Ningbo-side construction site of the Jintang subsea tunnel on the Ningbo–Zhoushan Railway, China’s first domestically developed TBM saturation pressurized entry system—nicknamed the “Deep-Sea Space Station”—has successfully completed its debut. The system carried out a pressurized TBM chamber entry operation at a depth of 75 meters, marking the first successful on-site application of China’s independently developed saturation pressurized entry technology. This milestone strengthens the country’s technical foundation for future deep-buried cross-sea tunnels and the development of deeper underground space.

According to the report, the “Deep-Sea Space Station” was jointly developed by China Railway 14th Bureau Group and the Shanghai Salvage Bureau of the Ministry of Transport. It features multiple functional modules, including the Ninghai (living) chamber, Tanhai (shuttle) chamber, and Zhenhai (control) chamber, enabling precise simulation of high-pressure subsea conditions. The system supports a maximum saturation working depth of up to 100 meters.

Once inside the “Deep-Sea Space Station,” workers live in the Ninghai chamber under pressure conditions equivalent to those on the seabed. Each day, they travel via the Tanhai shuttle chamber to the TBM located under the sea, entering the high-pressure workface directly to conduct equipment maintenance and cutter replacement operations.

IT Home notes that the Jintang subsea tunnel is the key controlling project of the entire Ningbo–Zhoushan Railway, stretching 16.18 kilometers, with the subsea TBM section alone reaching 11.21 kilometers. The TBM advancing from the Ningbo side—named “Yongzhou”—must navigate 24 transitions between soft and hard strata within the section. Hard rock and mixed soft-hard formations account for nearly 70% of the geology encountered, with a maximum rock strength of 191 MPa, underscoring the project’s high technical demands.

By applying saturation diving principles, the “Deep-Sea Space Station” keeps the gas state in workers’ bodies balanced with the external high-pressure environment. After a single pressurization, workers can operate continuously over multiple days without having to repeat lengthy decompression procedures after every entry. After each shift, they can return directly to the Ninghai chamber for rest and daily living.

Beyond breaking through depth limitations, the system also dramatically expands effective working time. Wu Yuli, a large-diameter TBM technology expert at China Railway 14th Bureau Group, stated that with the “Deep-Sea Space Station,” the team has already achieved 22 consecutive days of operation, inspected and replaced 46 cutters, and increased effective single-entry working time from 40 minutes to 8 hours. The system enables 24-hour rotational shifts among multiple teams, with a maximum operational cycle of up to 28 days.