At 10 a.m. on May 18, at the site of the Yangtze River shield tunneling crossing project of the China-Russia East Route of the National Pipeline Network Group in Nantong, Jiangsu, the Chinese shield machine "Changtong" was successfully launched, marking the official start of drilling for the Yangtze River shield tunneling crossing project of the China-Russia East Route. The project is the "throat" project of the China-Russia East Route, a major national energy artery, and is currently the oil and gas pipeline river-crossing shield project in the world with the longest single-direction shield tunneling distance, the greatest burial depth, the highest water pressure, the largest diameter, and the most complex construction environment.

Multiple Records Make It the "First Longest Tunnel Under the Yangtze" for Oil and Gas Pipelines

It is understood that the project crosses the Yangtze River in the form of a tunnel, with complex construction conditions and extremely high construction difficulty. The excavation of the north bank vertical shaft in Haimen and the lifting and installation of the shield machine down the shaft have already been completed in the earlier stage. This time, tunnel breakthrough and tunneling operations will begin.

The total length of the tunnel is 10.226 kilometers. It is currently the shield tunnel with the longest single-direction shield tunneling distance in the world's oil and gas field, and also China's first underwater tunnel with the longest long-distance single-head tunneling; the tunnel crown elevation at the lowest point of the project is -60.2 meters, and the maximum overburden thickness is 42.5 meters, both of which are the maximum design burial depths for oil and gas pipeline shield projects; the water pressure during shield construction is 0.73 MPa, making it the shield project with the highest water pressure at present; the excavation diameter is 7.95 meters, the tunnel inner diameter is 6.8 meters, and the outer diameter is 7.6 meters. Three pipelines with a diameter of 1,422 millimeters will be laid inside the tunnel, making it one of the projects with the largest diameter gas transmission pipelines in the world.

The "Changtong" shield machine specially developed for the project is the world's first atmospheric cutterhead shield machine with the smallest diameter (Φ7.95). It rolled off the production line at the end of March 2021, and on-site assembly and debugging began in April. Next, the "Changtong" shield machine will shoulder the heavy responsibility and tunnel at a speed of 450 meters per month, challenging five world records in the oil and gas field.

Ecology First: Creating a "Green Business Card" for Yangtze River Protection

The Yangtze River shield crossing point is located at the mouth of the Yangtze River, crossing structures such as the Yangtze River Class I waterway, anchorage grounds, and the Yangtze River levee, and is adjacent to existing and planned wharves such as Haixin Heavy Industry and China Merchants Heavy Industry; this area is also a protected area for the aquatic germplasm resources of Yangtze River tapertail anchovy, which places higher requirements on construction technology and methods.

During the project construction process, environmental protection measures such as slurry balance shield tunneling and sealed shipping of discarded slag are adopted, and labyrinth-type slurry tanks, multi-stage screening systems, and fine-particle centrifugal systems are comprehensively applied to ensure that slurry does not fall to the ground and discarded slag does not leak, achieving effective control of pollutant emissions and environmentally sensitive targets, attaining "zero leakage, zero discharge, and zero pollution," and protecting the natural ecology of the Yangtze River to the greatest extent.

"Russian Gas" Flows South to Help the Yangtze River Delta Achieve Dual Carbon Goals

The Yangtze River shield tunneling crossing project of the China-Russia East Route is the first key control project independently started and constructed after the establishment of the National Pipeline Network Group, and is the "throat" project of the China-Russia East Route, a major national energy artery. The China-Russia East Route (Hebei Yongqing-Shanghai) section to which the project belongs is interconnected with in-service pipelines such as the West-East Gas Pipeline Phase I and Phase II, with an annual gas transmission capacity of 18.9 billion cubic meters. Compared with coal burning, it can reduce carbon dioxide emissions by 81.44 million tons, sulfur dioxide emissions by 900,000 tons, nitrogen oxide emissions by 230,000 tons, and dust emissions by 420,000 tons. It contributes to improving the regional atmospheric environment, increasing China's clean energy supply, optimizing the energy structure, building a clean, low-carbon, safe, and efficient energy system, and achieving the goals of carbon peaking and carbon neutrality.

The project was officially launched at the end of July 2020, and construction was comprehensively advanced and accelerated in January 2021. The entire line is expected to be completed by 2025. After completion, "Russian gas" passing through the three northeastern provinces and the Beijing-Tianjin-Hebei region can be smoothly delivered to the Yangtze River Delta region, improving the emergency guarantee capacity for natural gas in the Yangtze River Delta.