China's first high-speed rail tunnel across the Yangtze River has officially entered the construction phase of shield tunneling

On June 16, the "Changjiang" shield machine of Chongqing Yangtze River Tunnel of Chongqing-Hunan high-speed Railway slowly turned the cutter head in the 149-meter-deep cave chamber in Nanshan, Chongqing, to start the most difficult river crossing operation, marking the country's first high-speed railway tunnel across the Yangtze River officially entered the shield tunneling phase.

Chongqing Yangtze River Tunnel starts from Chongqing Railway Station, and passes through municipal roads and Bridges, rail transit lines, housing buildings, civil air defense caves, Yangtze River Valley, and Nanshan Mountain. The tunnel as a whole highlights the complex characteristics of running through mountains, cities, rivers and water. The main line length is 11.942 kilometers, and the single-hole double-line tunnel is a heavy and difficult control project of the whole line. Survey and design by the Second Institute of China Railway, China Railway 14th Bureau Group construction.

According to reports, the innovative use of large-diameter shield machine assembly and disassembly technology in the hole in the design solves the bottleneck of the shield construction of the project which is limited to the starting or receiving site, and escorts the smooth implementation of the project.

According to the report, Chongqing Yangtze River tunnel is known as "the first tunnel of the Yangtze River high-speed railway", the shield section is 3845 meters long, and the river section is 1282 meters long. In order to overcome the problems, the project department of the 14th Bureau of China Railway under the guidance of Chongqing and Guizhou Railway Co., LTD., takes the intelligent construction as the guide, gives play to the core technical advantages of the 14th Bureau of large shield, and tailored a mud-water balance shield machine. This is the first shield tunnel in China that is completely installed, started, received and dismantled in the cave.

According to reports, Chongqing Yangtze River tunnel through the Yangtze River main channel when the maximum water depth of 42 meters, the minimum overburden thickness of only 10 meters, the maximum water pressure of 0.9 mpa (equivalent to the size of the nail to bear 9 kilograms of pressure), the "Yangtze River" shield machine cutter diameter of 12.66 meters, the total length of 142 meters, the total weight of about 3,500 tons, Adopt a number of latest configurations and technologies: high-precision gas-liquid pressure balance control technology, high pressure scouring system, heavy cutter with pressure, harmful gas automatic monitoring technology, main drive seal automatic pressure balance technology.

The first 2 sections of the heavy Guizhou Railway station, constructed by the 14th Bureau of China Railway, lead from Chongqing Station, connect to Chongqing East Railway Station, and pass through Yuzhong District and Nanan District of Chongqing. The total length of the line is 19.155 kilometers. The main project includes 3 tunnels and 5 subgrade sections, and the proportion of Bridges and tunnels is as high as 89.91%. At present, two tunnels have been penetrated, the bridge substructure has been completed, and the beam construction is being carried out.

The Chongqing-Hunan high-speed railway is an important part of Xia-Yu channel in the "eight vertical and eight horizontal" high-speed railway network planned by the national medium and long-term railway network, with a total length of nearly 800 kilometers, including the newly built Chongqing-Qianjiang Railway, the main line length of 269.5 kilometers, the design speed of 350 kilometers per hour, from Chongqing station, to the east through Yuzhong, South Bank, Banan, Nanchuan and Wulong five districts, Pengshui County, ending in Qianjiang District. It is a high-speed passenger transport communication channel between Chengdu-Chongqing city group, the middle reaches of the Yangtze River city group and the West Coast city group.