Dalian metro line 5 tunneled 936 meters across the sea

At present, dalian metro line 5 cross-sea big shield "haihong" has been smoothly tunneling 936 meters, is now average monthly speed of 90 meters. The total length of the tunnel is 2,870 meters. It has been 1/3 completed since the launch of the tunnel on January 18 this year.

The submarine shield construction project of dalian metro line 5 belongs to long-distance, hard rock and high water pressure construction through karst cave area, and the tunnel passes through 1538 meters of medium-strong karst development area, with an average cave detection rate of 59%. The largest cave is 29.8 meters high, and there are more small caves of several meters. During the early exploration, the staff has detected that the whole cross-sea section may encounter three large cave groups, and so far, they have passed two. There are too many large karst caves, so we can only use large diameter shield tunneling machine to reduce construction and operation risks.

At the operating position of the "haihong" shield tunneling machine, entering the 189-meter-long shield tunneling machine, not only the rumbling increased, but also the temperature increased significantly. Due to the high heat generated by grinding the rock, plus the heat generated by the various machines running in the shield machine, the closer you are to the cutter head, the hotter it gets.

As for the safety problem, the field staff said, "there are more than 200 tools in the cutter tray, and this is the longest distance of hard rock tunneling into the large shield tunnel at present. The stone is hard in the karst area, the face of the palm is uneven, and the tools are often sharpened and broken, so it is common for workers to enter the central warehouse and change the knives. The cutting plate in the front is tunneling, and the lifting of the pipe segment in the back is also proceeding simultaneously. The pipe segment of the cross-sea tunnel is 50 centimeters thick, while the tube segment of the ordinary subway tunnel is about 35 centimeters, so there is no need to worry about the safety issue."

Every 150 meters, a colorful neon strip will appear on the tube wall of the cross-sea tunnel in the shuttle zone of line 5, which is specially installed to relieve the visual fatigue of the driver of the transport vehicle. At a depth of more than 30 meters below the sea surface, this project, which is defined by industry experts as a worldwide difficult project with great difficulty, high safety risk and no precedent to follow, is being carried out step by step in an orderly manner. The technology is precise and precise, and the atmosphere at the site is not tense and dignified.