China Completes Record-Breaking Underwater Shield Tunnel

Jinan, the capital of Shandong Province in East China and home to 9.4 million people, has made global headlines. Crews there have successfully completed the construction of the world’s largest-diameter underwater shield tunnel.

The China Railway 14th Bureau Group is using the world’s largest tunnel boring machine to excavate a 3.6-mile (5,755 m) tunnel. While the main section is still under construction, the 2-mile (3,290 m) underwater shield segment is complete.

At 55.8 feet (17 meters) in diameter, it’s the largest tunnel of its kind, compared to the Channel Tunnel’s 25-foot (7.6 meters) public rail tunnels.

The Jinan Huanggang tunnel will have six lanes in a double-decker design and a 60 km/h (37 mph) speed limit. This vital north-south passage will cross China’s Yellow River, boosting connectivity between Jinan and an economically transformative region.

Jinan Tunnel Sets Speed Record with 110-Day Completion of Underwater Shielding Section

In addition to its world-record size, the 14th Bureau Group also set a record for the speed of construction. Crews began tunneling on September 1, 2024, and completed the underwater shielding section in just 110 days. The Shanhe shield machine achieved a daily advancement rate of 52.5 to 59 feet (16 to 18 meters), setting a new record for 17-meter-class shield construction.

The tunnel boring machine, a Herrenknecht “Shanhe” Shield Machine, has a 57.4-foot (17.5-meter) excavation diameter—about five stories tall. Powered by a 7,510 hp (5,600 kW) motor, it delivers an astounding 25,827,209 lb-ft (35,017 kNm) of torque. Designed to withstand up to 7.5 bar of pressure, it can also manage 15 bar in the excavation chamber with the help of a specialized air cushion that maintains stability.

The TBM’s cutting wheel is equipped with a flushing system to prevent clogging, and a telescopic camera system monitors the cutting bits and tunnel face. This setup reduces the need for time-consuming and dangerous hyperbaric interventions.

The Jinan Huanggang Road Yellow River Crossing Tunnel is expected to be completed in late 2025.

Read Original Article: New Atlas

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