Workers in China have achieved a remarkable feat by completing the world’s largest-diameter underwater shield tunnel. This milestone marks a significant advancement in engineering, as the two-mile section of the underwater shield tunnel was successfully completed. The section has an impressive diameter of 55.8 feet (17 meters) and incorporates 500 pipe rings for underwater shielding.
An Ambitious Tunnel Project
The ongoing tunnel project, situated 98 feet below the banks of the Yellow River, spans 3.6 miles and is designed to improve regional connectivity. Once completed, the tunnel will provide a vital two-way route for vehicles, offering three lanes in each direction. The tunnel is also designed for a speed of 37.2 miles per hour (60 km/h), enhancing transportation efficiency across the region. The project is located in Jinan, the capital of Shandong Province in eastern China, and is being built by China Railway 14th Bureau Group Co., Ltd.
The Shanhe Boring Machine: A Technological Marvel
One of the key factors behind the success of this monumental task is the groundbreaking machinery used during construction. The “Shanhe” shield machine, an advanced boring machine, was crucial in completing the underwater shielding. The tunnel’s construction began on September 1, 2024, and in just 110 days, the workers, using this cutting-edge equipment, completed the underwater shield.
The “Shanhe” machine, manufactured by Herrenknecht, is a mixshield boring machine with a massive excavation diameter of 57.5 feet, about the size of a five-story building. It is capable of advancing 52.5 to 59 feet per day and an impressive 1,396.6 feet per month, setting a new world record for 17-meter-class shield construction. The cutterhead driver of the “Shanhe” boasts 7,510 horsepower and delivers around 25,827,209 lb-ft (35,017 kNm) of torque, comparable to 26 million lb-ft of electric motors and hydraulic power.
The machine is equipped with several innovative features to ensure its effectiveness and safety. These include a flushing system to prevent clogging, a telescopic camera system to reduce the need for manual intervention, and a specialized automatic air cushion that balances pressure and maintains stability, preventing potential collapse or flooding. Additionally, the “Shanhe” can withstand an extraordinary 7.5 times the normal atmospheric pressure (7.5 bar), with its excavation chamber capable of handling up to 15 bar of pressure.
Overcoming Construction Challenges
Despite the impressive capabilities of the “Shanhe” boring machine, the construction team faced several challenges. One of the primary issues was waste slurry treatment, a common problem in tunnel construction. However, the team developed a pioneering solution to ensure environmentally friendly tunneling. They implemented a dual-line pipeline hydraulic quarrying device, jaw crushers, and a waste slurry concentration and filter press system, ensuring the project’s environmental sustainability.
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A Monumental Infrastructure Project
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The Yellow River tunnel, with a diameter of 55.8 feet, is the largest of its kind. However, it is not the longest underwater tunnel in the world. The Seikan Tunnel in Japan holds the record for the longest underwater tunnel at 33.46 miles, while the Channel Tunnel between the UK and France stretches for 31.4 miles. Despite this, the Jinan Huanggang Road Tunnel will play a crucial role in improving connectivity in Shandong Province, particularly by linking the urban area on the south side of the Yellow River with a new state-level strategic pilot zone for free trade, innovation, and reform on the north side of the city.
Completion Timeline and Future Outlook
The completion of the Jinan Huanggang Road Tunnel is expected around late 2025. When finished, it will be a significant infrastructure project, revolutionizing transportation across the Yellow River. Not only will it ease traffic flow, but it will also enhance regional connectivity and support China’s economic development plans.
As this monumental tunnel project continues, it stands as a testament to China’s engineering prowess and ambition. With groundbreaking technology, efficient machinery, and innovative construction solutions, the Jinan Huanggang Road Tunnel is set to become a symbol of modern infrastructure development.
