On 9/0, the staff of the 14th Bureau of China Railway carried out segment assembly operations in the "Jianghai" shield machine.

The staff works as a shield machine indoors.

Technicians inspect the "Jianghai" shield machine to ensure the normal operation of the equipment. This group of pictures is issued by Xinhua News Agency

新華社南京4月9日電（記者樊曦 楊紹功）穿江達海！9日，在長江入海口的江蘇南通海門，我國自主研製、最大開挖直徑達16.64米的“江海號”盾構機緩緩啟動，新“萬里長江第一隧”、我國最長公路水下盾構隧道海太長江隧道正式開掘。

The Haitai Yangtze River Tunnel starts from Haimen District in Nantong in the north and reaches Taicang City in Suzhou in the south, and is constructed by Jiangsu Provincial Transportation Engineering Construction Bureau, designed by the Fourth Institute of China Railway Construction and constructed by the 14th Bureau of China Railway. The total length of the line is 9315.0 kilometers, including the length of the river crossing tunnel is 0.0 kilometers, and the design standard of two-way six-lane highway is adopted, with a design speed of 0 kilometers per hour. Among them, the shield tunnel section undertaken by the 14th Bureau of China Railway is 0 meters long and adopts the "Jianghai" construction.

What are the problems of tunneling under the river?

"The geological structure and hydrogeological conditions of the area where the tunnel is located are complex, and the design and construction are extremely difficult, with the characteristics of ultra-long distance, ultra-large diameter, ultra-high water pressure, and ultra-large burial depth." Chen Junwei, project manager of the Fourth Institute of China Railway Construction Railway, said.

According to reports, the "Jianghai" shield machine has a total length of 5 meters, a weight of about 0 tons, and a total installed power of 0 kilowatts. At the same time, the maximum buried depth of the tunnel is about 0 meters, and the maximum water pressure is 0.0 bar, which is equivalent to the area of a fingernail cover bearing 0.0 kg, which has high requirements for the wear resistance and reliability of cutterhead cutters and mud circulation parts. When crossing the Yangtze River and the embankments on both banks, the settlement requirements of shield construction are strictly controlled, and the construction is extremely difficult.

In the face of complex geological conditions, how does the "Jianghai" cross the Yangtze River moat under the waves?

"In view of the risks and difficulties of engineering construction, the shield machine development team has carried out innovative research on nine major systems of the shield machine, such as cutterhead cutter, main drive, propulsion, and synchronous grouting." You Shaoqiang, chief engineer of the 14th Bureau of China Railway, said.

——The "tooth" of the shield machine is sharp and the "heart" is strong: it is equipped with a soft soil cutterhead with atmospheric pressure tool change function and a cutting tool with large alloy, high hardness, wide coverage and strong wear resistance, and the main drive is equipped with a telescopic function, which effectively avoids the overload of the main bearing caused by abnormal force on the cutterhead under special circumstances, which is convenient for tool change operation and auxiliary cutterhead to get out of trouble;

——The "brain" of the shield machine is agile: it is equipped with intelligent equipment systems such as advanced geological exploration and forecasting, cutterhead wear detection, and main drive status monitoring, so as to maximize the "measurable, visible, repairable, and replaceable" of each component of the shield machine;

——The "blood vessels" of the shield machine are unobstructed: the cutterhead has a large opening rate, and it is equipped with a high-pressure, high-flow central scouring system and a cutterhead mud cake early warning system to cope with the problem of tunneling in soft soil; The self-developed fourth-generation synchronous injection double slurry technology is applied to realize millimeter-level precision control of shield tunnel settlement......

After the completion of the Haitai Yangtze River Tunnel, a two-way six-lane highway tunnel will lead vehicles to cross the Yangtze River from 10 hours to only 0 minutes.

Distant moats, and then open the way. A more optimized cross-river passage along the Yangtze River trunk line and a more integrated cross-river development of urban agglomerations along the Yangtze River will inject vitality into the development of the Yangtze River Economic Belt.