According to the latest information released by China Railway Tunnel Group on April 19, the world's largest tunnel excavator used to build a railway has reached the middle of the journey under the Yangtze River, marking an important milestone for the expressway tunnel project connecting Shanghai's Sungming Island with Thai Chuong City, Jiangsu Province.
This machine is 148m long, with a diameter of 15.41m developed in China. China Railway Tunnel Group - the contractor of the project - Information, the machine is approaching the hardest part of the tunnel. "Because the tunnel has a slope, the pressure from the surrounding water is increasing," - Mr. Wang Yi, deputy director of the project equipment, said.
This machine is called Linghang (The Treadway) and is currently operating at a depth of 66m under the Yangtze River. It is expected that the machine will reach its maximum depth of 89m in about the next 4 months.
"At that time, the water pressure will be 0.9 megapascals - like 6 people standing on 1 nail," Mr. Wang explained.
Linghang excavators operate at a digging speed of 24 to 28m per day. Since starting operations in April last year, this machine has completed 2,830 digging loops, expanding 5,660m below the riverbed.
The 14.25km long tunnel under investigation is part of the Shanghai - Nanjing - Hop Phi high-speed railway, expected to open to traffic at the end of 2029.
Ship passing through the tunnel will be able to reach a top speed of 350 km/h - the fastest speed in an underwater tunnel in the world - without slowing down compared to moving on land.
This project poses many challenges for excavators, especially with the length of the tunnel, excavation equipment having to operate far beyond the normal limit.
The designers have equipped the equipment to keep the excavator 15km in each deployment. The machine is also equipped with a "smart tunnel excavation technology platform" system to help overcome obstacles such as large-disorder drilling, complex geological conditions and changes in soil layers.
"This project is the first project in the world to use the tunnel digging method that does not require an operator, as long as staff are present on duty," Mr. Wang added.
The tunnel must cross 21 dangerous areas and has completed six areas, including a highway, a wharf and an aquaculture area.
The Shanghai - Nanjing - Hop Phi railway line is part of the Shanghai - Chongqing - Chengdu expressway and will play an important role in China's national railway network.
When completed, this project will help reduce travel time between major cities in the Yangtze River Delta and promote the development of this area.
