The title of "infrastructure madness" is well deserved in China!
On May 16, a world-class transportation project in Zhoushan ushered in the start of construction, China wants to build a high-speed rail tunnel under the sea to run through the mainland and the Zhoushan Islands, this project will break the history of Zhoushan without trains.
But at the same time, the tunnel is one of the longest and most complex projects in the world, and even though Japan and the United Kingdom have precedents for construction, they cannot be connected to high-speed rail due to speed restrictions.
So how difficult is this tunnel to build, and how does the mainland overcome it?
The world's first high-speed rail tunnel
Since we started our initial contact with high-speed rail in 08, and now our speed has amazed the world, and what is even more worthy of cheering is that we will usher in the first undersea high-speed rail tunnel next, this news is all exciting.
According to official reports, we want to open the high-speed rail tunnel under the sea from Ningbo and Zhoushan, and we have already begun to "cross the sea", and if it is built, it will be the most historic moment.
The entire Yongzhou railway is 77 kilometers long, during which nearly 17 kilometers of underwater tunnels will be built under the Jintang waterway, which is expected to be opened to traffic in all aspects in four years according to the plan, with a speed of up to 250 kilometers per hour, which can be fully opened to high-speed rail.
Perhaps compared to the Seikan Tunnel and the English Channel Tunnel, although we do not have as many kilometers under the sea as Japan and the United Kingdom, we have to say that this passage can meet the needs of high-speed rail walking, which is beyond their reach at present.
It is worth mentioning that after the whole road is opened to traffic, it will only take half an hour to reach between the two places, so you can imagine how convenient it will be for residents of the two places to travel and economic development.
But it's easy to say, but it's hard to do, you must know that the construction of an ordinary high-speed railway is certainly effortless for our current technology, but the difficulty is that there is a section of underwater tunnel during the period, and the premise must also meet the needs of high-speed rail.
The construction of a single-hole double-track high-speed rail tunnel is undoubtedly the most difficult key project in the entire high-speed rail section, and it will mean whether we can achieve the opening of traffic in four years as agreed.
So how hard is it to build it?
How hard is it to build?
When it comes to undersea tunnels, some people may think that it is the same, it is not a terrestrial environment to an underwater environment, and now that our technology is so advanced, it must be very easy to get it.
As everyone knows, it is precisely because this section of the road is under the sea that it is not only built through the city and the sea, but also has to open up the passage between the ground and the sea, and the underwater project must be done in the changing environment.
According to the news, the underwater tunnel to be built will be carried out at a distance of 78 meters from the ground, the height of the water will be 39 meters deep, the outer diameter of the segment will need to reach 14 meters, and the entire road will be excavated for 16.18 kilometers.
With a total length of 135 meters, an excavation diameter of 14.57 meters, and a weight of more than 4,000 tons, it is almost impossible to achieve the difficulty of a single EPBM.
In the face of such a situation, our technicians adopted the practice of "two-way running", so that the "Yongzhou" and "Dinghai" shield machines started to work from both sides at the same time and completed the docking under the sea.
First of all, Ningbo was taken as the starting point, and the "Yongzhou" was excavated into the sea under the city, during which after digging 58 meters, it was necessary to pass through important routes such as oil pipelines and power pipelines, and also pass through more than 40 kinds of risk sources and 12 layers of hard rock bottom.
In order to get rid of this problem, the technicians specially improved the cutterhead design of the shield machine and used the repeated scouring function to prevent the adhesion of the soil.
The most inevitable underwater project is the problem of water pressure, to work at a depth of 78 meters on the seabed, which is very difficult for the shield machine, in order to resist the water pressure of nearly 100 meters, the shield machine can only do internal work and closed treatment.
Of course, these external conditions are not a problem of water pressure and geology, and it is easy for the shield machine to move forward, but how to accurately dock the two machines and successfully complete the exit under water is a necessary consideration for this project.
Indeed, it is not easy to complete the docking under the invisible and untouchable underwater, in order to achieve precise docking, our technicians specially use the six-piece bucket positioning system, so that only one side of the machine first reaches the designated position, and then the other machine is sent over through manual positioning, during which the docking accuracy is controlled in the range of two centimeters.
In order to do a good job in the aftermath, our technicians gave priority to this layer, they improved the machine to make it adopt a double-shell design, when the two machines are docked, and then underwater to disassemble and get rid of the interior, so that only the shell remains in the tunnel, the whole process is like "golden cicada shelling".
The project is not yet complete, because the seabed is extremely corrosive, our technician took into account the durability of the tunnel, and he deliberately added anti-corrosion technology to the materials when designing the segments, which can be described as very thoughtful.
According to sources, the tunnel will be completed in two years, and the entire Yongzhou railway will be fully opened to traffic in four years, which has to be said to be shocked by China's infrastructure capacity.
But unexpectedly, this project has made everyone question, they think that the Jintang Bridge has already been built, why not turn the high-speed rail track into a sea bridge, but build a tunnel under the sea?
Why tunneling?
For a long time, in the battle of bridges and tunnels, many people are very optimistic about "building bridges", the whole project is less than the funds consumed in tunnel construction, not to mention, after the construction is completed, it does not need to be maintained from time to time, and it also has a landscape.
On the other hand, the tunnel project is either under the mountain, underground, or under the sea, not to mention the lot of money, there are many factors to consider, and it is very difficult to build, even if it is built, it has to be maintained and operated frequently.
Therefore, under many considerations, people are more optimistic about building bridges, after all, this is a significant project, spending less money and quick results, and there is no need to worry too much afterwards, and now many areas choose to use bridges as connections for convenient transportation.
But as everyone knows, what we can think of, the country has already thought that the reason why the reason why the construction of the undersea tunnel is spent a lot of money is naturally out of consideration for the development of the port, to reduce some necessary economic impact.
It is important to know that the Jintang Waterway, as the most important access channel of Zhoushan Port, carries the economic road, and tens of thousands of transport ships pass through here every year.
However, it is different to build an undersea tunnel, which not only will not affect the free entry and exit of ships of more than 100,000 tons, but also bring great convenience to people traveling in the two places, and play a role in boosting the local economic development.
The author thinks
Magnificent projects are always prepared for great development, the future of China has a strong you and I can't imagine, there is no problem that can hinder us, once again for China's infrastructure development amazed!
Resources:
Guangming.com2024-05-16
Iconic moment! The world's largest undersea high-speed rail tunnel begins to "cross the sea" today
China.com2023-05-08
The excavation of the Jintang undersea tunnel of the Yongzhou Railway Control Project is the first in the world, and the gold content is not ordinary