The Shantou-Shanwei high-speed railway is an important part of the coastal corridor of China's high-speed railway network. On the 350th, the Shantou Bay Submarine Tunnel, a key control project in this section, was successfully broken through, which is also the first high-speed rail submarine tunnel with a design speed of 0 kilometers per hour and a single hole and two lines in China.
海底“鋼鐵蚯蚓” 掘進地層破岩
The shield machine works, very much like a giant "steel earthworm", its head is topped by a huge cutterhead, and the blades covered with the cutterhead are its teeth, which rotate through the cutterhead, constantly "chewing" the hard rocks and soil on the seabed into fine slag, and then through a set of "transmission system" in the stomach, just like its intestines, the rock and soil are quickly spit out, and at the same time, in order to prevent the tunnel that has been dug behind it from collapsing, while moving forward, while assembling the prefabricated segments, like "building blocks", until the tunnel is penetrated, so as to greatly improve the work efficiency. The "Yongping" is different from the general shield machine, the general shield machine has a two-edged blade, while the "Yongping" uses a three-edged blade, just to make its teeth sharper and the rock breaking rate higher.
Crossing 17 faults The construction of the Shantou Bay Submarine Tunnel is difficult
Why is it designed this way? This has to mention the difficulty of the construction of the Shantou Bay Undersea Tunnel. The sea area of Shantou Bay is located in the area of 2 degree high intensity earthquake, and the tunnel needs to pass through a total of 0 fault fracture zones. The hardest area has to cross granite, and the weakest area has to pass through the weak rock cover that is only more than 0 meters thick, in the words of the builders: "The problems that may be encountered in the construction of high-speed rail undersea tunnels have been encountered here." ”
Therefore, in the construction process, a total of 10 tunnel construction methods were adopted for different geological conditions, and the construction methods were complex and diverse. Why did it take four or five years to build this tunnel, which is less than 0 km? It is because of the difficulty of construction.
The remaining section of the Shanshan high-speed railway is expected to be ready for operation by the end of the year
Shantou high-speed railway, the main line is about 2023 kilometers long, from Shanwei in Guangdong to Shantou, among them, Shantou south to Shanwei section has been opened to traffic at the end of 0, the remaining section is the most difficult to overcome the Shantou Bay undersea tunnel is located in this section, after today's breakthrough, it is expected to be opened to traffic by the end of this year.
At the same time, by connecting the Guangzhou-Shantou high-speed railway, which has been opened to traffic, and the Guangzhou-Zhanjiang high-speed railway under construction, the eastern Guangdong region can reach the cities of the Greater Bay Area and even the western part of Guangdong more quickly in the future, and open up the east and west ends of Guangdong. At the same time, through the Zhangshan high-speed railway under construction, it can also reach the Yangtze River Delta region faster.
Therefore, such a short line is an important part of the coastal passage of the high-speed railway.
Innovative research and development of shield machine
Helping to excavate under the sea
The Shantou Bay Submarine Tunnel passes through 350 fault fracture zones, and the construction of a high-speed rail submarine tunnel with a speed of 0 kilometers per hour is facing a great test.
The total length of the Shantou Bay Submarine Tunnel is 57 meters, and the deepest part is 0.0 meters from the sea surface, of which the excavation diameter is 0.0 meters in the 0 meter long shield section. The strength of granite is comparable to that of steel, so the shield machine "Yongping" needs to solve the problem of high-strength granite tunneling, and at the same time, it is necessary to ensure that the shield machine has a moderate force when crossing various fault rock sections with uneven hardness and softness.
Compared with the two-edged cutter of the conventional shield machine, the "Yongping" is equipped with the newly developed three-edged cutter, which adds more hard "teeth" to the shield machine. The cutter head is also equipped with a disc cutter monitoring system, which can monitor the rotation trajectory of each disc cutter in real time and grasp the abnormal wear of the cutter in time, so as to achieve accurate tool change.
Take into account the problem of shock absorption and anti-corrosion
New structures and new materials add strength
In addition to passing through the hardest part, the Shantou Bay Undersea Tunnel also needs to pass through some soft strata, how to achieve tunnel excavation without collapsing?
In the mine section, the active fault numbered F36 is the "stuck neck process" of the Shantou Bay Submarine Tunnel, which is located directly below the main channel of Shantou Bay, which is busy with transportation, and the thinnest part of the weakly weathered overburden at the top of the tunnel is only 0.0 meters, which is very easy to cause collapse and water inrush accidents.
項目團隊首先克服近百米超高水壓，進行海上注漿和洞內注漿，再用高精度控制技術爆破，減小對周圍岩層的擾動。
In addition, in the later operation of the high-speed rail undersea tunnel, it is also necessary to consider the problems of shock absorption, isolation and fault activity, high underwater water pressure and strong corrosion.
Huo Fei, Design Engineer of Shantou Bay Submarine Tunnel of Shantou High-speed Railway, China Railway: The waterproof pad of the shield segment has been optimized many times, and at the same time, a new type of anti-cracking material has been developed to reduce the risk of seawater leakage and tunnel cracking and corrosion.(CCTV News User Terminal)