With the rapid development of science and technology, human beings have become more and more in-depth in the exploration and use of underground space. Recently, an exciting news came from Changsha: the giant shield machine "Dinghai" jointly developed by China Railway 11th Bureau and China Railway Construction Heavy Industry Co., Ltd. has successfully rolled off the assembly line, and it will become the world's longest and largest submarine high-speed rail tunnel - Yongzhou Railway Jintang Submarine Tunnel construction assistant.
The reason why this shield machine is named "Dinghai" means that it will be steadily advancing on the seabed like a needle in Dinghai, escorting the construction of high-speed rail tunnels. And its impressive size and weight are even more impressive: the cutterhead has an excavation diameter of up to 1457 meters, the length of the whole machine is about 135 meters, and the total weight is about 4,350 tons, which is equivalent to 8 times the weight of an ordinary shield machine. Such a huge equipment is enough to show China's strong strength in the field of underground engineering.
As a world-class engineering problem, the construction difficulty of the Jintang Submarine Tunnel of the Yongzhou Railway can be imagined. The complex and changeable subsea environment, high water pressure and chemical corrosion have brought great challenges to tunnel construction. However, the advent of the "Dinghai" shield machine provides a powerful solution to this problem.
First of all, the "Dinghai" shield machine has the ability to withstand extremely high water pressure. When excavating a tunnel at the bottom of the sea, it needs to withstand a maximum of 085 megapascals of water pressure, which is more than 12 times the water pressure of ordinary tap water. In order to meet this challenge, the Dinghai shield machine uses special designs and materials to ensure that it can work stably in high water pressure environments.
Secondly, chemical corrosion of the subsea environment is also a major problem in tunnel construction. In order to resist the corrosion of seawater, the "Dinghai" shield machine uses a cement shell composed of cement slurry and additives in the outer layer of the segment. During the TBM tunneling process, this layer of cement shell can be simultaneously filled on the outside of the segment to form a closed shell, which effectively prevents water leakage and seawater corrosion in the tunnel.
In addition to coping with the challenges of the seabed environment, the "Dinghai" shield machine is also equipped with an advanced geological prediction system. This system uses the vibration signal generated by the cutterhead disc cutter rock breaking of the shield machine as the seismic source to accurately detect and improve the geological conditions within the range of 50-100 meters ahead. By grasping the geological information of the tunnel in advance, engineers can conduct early warning research and judgment in time to ensure safety and controllability in the construction process.
It is worth mentioning that the "Dinghai" shield machine also has excellent performance in precise docking. The Jintang Submarine Tunnel is constructed using the two-way shield method, which requires the shield machines that are constructed separately from both ends and go in opposite directions to achieve a very high level of accuracy during docking. Despite the cutterhead excavation diameter reached 1457 meters, but the docking error (radial misalignment) needs to be controlled within 20 mm, which is smaller than the diameter of a pennie. In order to achieve this precise docking, the "Dinghai" shield machine is equipped with a VMT guidance system to provide accurate guidance services and attitude control for shield tunneling.
In terms of design, the "Dinghai" shield machine adopts a double-layer shell structure. This design not only improves the overall stability of the shield machine, but also facilitates the dismantling of the machine in the tunnel. During the dismantling process, the shield ejector can be pulled out from the inside and then removed from the other parts separately. The outer shell remains in the tunnel as a permanent supporting structure, further enhancing the robustness of the tunnel.
To sum up, the successful launch of the "Dinghai" shield machine marks another major breakthrough in the field of underground engineering in China. It will help the construction of the Jintang Submarine Tunnel of the Yongzhou Railway and provide a strong guarantee for the construction of the undersea high-speed rail tunnel. In the future, with the continuous progress of science and technology and the emergence of innovative achievements, we have reason to believe that human beings will be able to better use and expand underground space resources and inject new vitality into social development.
Technology**