China has completed and opened the world’s largest-diameter underwater shield tunnel in Jinan, Shandong Province, according to Xinhua News Agency.
The tunnel passes beneath the Yellow River and uses a single-bore, double-deck design to carry traffic on two levels. Its opening adds a major piece of underground transport infrastructure to the city while demonstrating advances in large-scale tunnel construction.
Tunnel Design And Scale
The tunnel is about 5,755 meters long and has a designed speed of 60 kilometers per hour. Its shield-built section extends for about 3,290 meters and was excavated with a tunnel boring machine (TBM), measuring 17.5 meters in diameter. A TBM is a large machine that cuts through soil and rock while supporting the surrounding ground as the tunnel is built.
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The project is also the first single-bore, double-deck shield tunnel in China to pass beneath the Yellow River. Instead of building two separate tunnels, the design places two traffic levels inside one large tunnel structure. This approach allows the project to use a single underground passage for both decks while crossing a major river corridor.
Crossing A Difficult Route
The construction route presented several difficult conditions, including the Yellow River itself and its embankment. Engineers had to carefully manage ground movement because changes in soil pressure beneath the river and embankment could affect surface stability. The project team addressed 28 major technical challenges during construction.
These challenges included controlling excavation stability and limiting settlement as the TBM passed beneath the Yellow River embankment.
Engineers also worked on preventing large tunnel segments from rising during construction and improving the treatment of the large volumes of slurry produced by excavation. Managing these factors was essential for maintaining construction safety and protecting the surrounding environment.
Record Pace During Excavation
The tunnel achieved a maximum excavation rate of 18 meters in a single day. Its monthly advance reached 426 meters, setting a world record for shield tunneling in the 17-meter class. These figures reflect the scale of the equipment and the pace maintained during the underground construction work.
The project also required the TBM to operate through a complex geological and hydrological environment. Its large excavation diameter made ground control particularly important during the river crossing. The completed tunnel shows how larger shield machines are being used for increasingly complex urban infrastructure projects.
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China Expands Tunnel Technology
China’s shield tunneling sector has expanded in recent years as demand for underground transport and infrastructure has increased. Shield machines have become important equipment for projects that require tunnels to be built beneath cities, rivers and other difficult areas. Chinese experts say the industry is also moving toward greater use of intelligent systems and more efficient construction methods.
The development is not limited to projects inside China, as Chinese tunnel boring technology is also expanding into international markets.
Improvements in machine design, construction control and project management are supporting this wider use. The industry is increasingly shifting from large-scale application toward higher levels of efficiency, intelligence and global competitiveness.
The Jinan tunnel therefore represents both a local transport project and a larger trend in underground engineering. Its combination of a 17.5-meter TBM, a double-deck layout and a Yellow River crossing required engineers to manage several demanding construction conditions at once.
As China continues to expand its underground infrastructure and equipment exports, such projects are likely to shape the next stage of shield tunneling technology.
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