Reborn Technology Scholar

Currently, the longest undersea tunnel in the world is the Seikan Undersea Tunnel built in the Tsugaru Strait of the island nation. It is 53.85 kilometers long. It starts from Hamana, Imabetsu Town, Aomori Prefecture in the south, and Yuri, Chinai Town, Hokkaido in the north. It was constructed from 1964 to

It took 23 years to complete in 1987. The main tunnel of this tunnel is 53.9 kilometers long, including 23.3 kilometers of the submarine part, 13.55 kilometers of the road part on the Honshu side, and 17 kilometers on the Hokkaido side. The tunnel was completed and opened to traffic.

The history of transportation between Honshu and Hokkaido in Japan was based solely on sea transport.

The Seikan Undersea Tunnel has always been the pride of Japan's architectural history. It is regarded by Japan as a symbol of high-tech technology. Like Japan's high-speed rail, it is constantly promoted to the outside world.

There is no doubt that once the Bohai Tunnel is put into construction and completed, with its length of more than 100 kilometers, it will easily surpass the Seikan Tunnel and become the world's largest undersea tunnel.

By then, China's world-renowned achievements in infrastructure construction will inevitably include a Bohai Tunnel! After all, considering the difficulty of construction, this Bohai Tunnel will also be on top of the Hong Kong-Zhuhai-Macao Bridge.

Qin Yuanqing checked some information. The Bohai Tunnel project is really a huge national project, with a planned investment of 200 billion yuan. It can be said that this is probably the largest investment amount ever seen in a single project. After all, the Three Gorges Dam was

The total investment in the dam project is only over 90 billion yuan. The reason why the total static investment of the Three Gorges Project reaches 200 billion yuan is because it includes resettlement, land acquisition, etc.

For example, the Hong Kong-Zhuhai-Macao Bridge, which is still under construction, is expected to cost just over 100 billion when completed.

In other words, the investment in the Bohai Tunnel is enough to build two Hong Kong-Zhuhai-Macao bridges.

Moreover, 200 billion yuan is only an estimated investment. Often for such large-scale projects, additional investment is common at a later stage. The final total investment may reach 300 billion yuan or even 400 billion yuan.

A very important reason why the cost is so high is that the construction of undersea tunnels is difficult and requires high technology, so the cost is naturally much higher than that of bridges.

"The country's generosity is really getting bigger and bigger now, and 200 billion yuan has begun to be used as the cut-off point for big generosity!" Qin Yuanqing said with emotion.

The investment in the three large hydropower stations in the Yarlung Zangbo River Basin is also 200 billion yuan. Despite all kinds of disturbances, in the face of China's firm attitude and absolute strength, the three large hydropower stations have entered the construction stage. The investment in the ten third-generation nuclear power plants is actually

It also uses 200 billion yuan as the starting point.

Now, we have to add this Bohai Tunnel project!

These large-scale infrastructure projects are undoubtedly led by state forces. It is impossible for private companies to invest in such projects with long construction cycles and long cost recovery cycles, and the construction technology is basically in the hands of state-owned enterprises.

So don’t always criticize state-owned enterprises. State-owned enterprises do indeed do a lot of things that contribute to the national economy and people’s livelihood.

In the evening, a car came to the Shahe campus to pick up Qin Yuanqing. After some identity verification, Qin Yuanqing got in the car. After arriving at the airport, he met up with his superiors and arrived in Yancheng City.

At exactly 9:00 the next morning, when Qin Yuanqing entered the venue with his leaders, he took a quick glance and immediately understood the country's determination. If nothing else goes wrong, the Bohai Tunnel project will be launched.

Look at this expert group. In addition to Qin Yuanqing, there are ten academicians of the Chinese Academy of Engineering and seven academicians of the Chinese Academy of Sciences!

In the conference room, everyone else looked surprised when they saw Qin Yuanqing accompanying the leader into the conference room, and then they all looked thoughtful.

The host of the meeting, a leader from Shandong Province, introduced the expert group. In addition to as many as eighteen academicians, there are also fifty-eight professors from major universities, seventy-nine professor-level senior engineers, and national brands such as China Railway Tunnel Group.

There were more than 200 people in the conference room, including chief engineers, deputy chief engineers and other technical experts from large enterprises.

Everyone realized that this Bohai Tunnel planning meeting was different from previous meetings, and the specifications had been improved by more than two levels.

In the past Bohai Tunnel planning meetings, academicians also participated, but they were probably only two, three, or three or four. Most of the people who chaired the meeting were local city leaders, but this time it was the relevant leaders of Shandong Province who chaired the meeting, and there were also higher-level officials.

Leaders attended the meeting, and even Qin Yuanqing, a leading figure in the field of scientific research in China, attended the meeting.

It seems that after so many years of deliberation, the superiors are finally getting serious about the Bohai Tunnel plan.

Look at this conference room. Among the technical staff, every one is at least a professor-level scientific researcher or engineer. Associate professors and senior engineers are not eligible to participate.

Qin Yuanqing watched the technical staff talking one by one and took notes carefully. The technical staff participating in this meeting had been involved in the Bohai Tunnel Project for a long time in the early stage. They knew much more about the Bohai Tunnel Project than he did. They all had their own thoughts about the Bohai Sea Tunnel.

Thoughts on tunnel plans.

This meeting was also a collision of sparks of thinking and wisdom.

Due to the special geographical location of the Bohai Strait, all transportation routes of various ports in the Bohai Sea pass through here. Giant ships of 100,000 tons and 200,000 tons often appear there. In the future, there will even be giant ships of 300,000 tons or even 400,000 tons.

This means that only undersea tunnels can be built in this place, and there is no possibility of building bridges.

Not to mention, the Bohai Strait is a strategic military location and even has aircraft carriers passing through it from time to time, so there is no possibility of building a bridge.

There are three main methods for constructing undersea tunnels, namely the burying method, the shield method, and the boring machine method.

To understand it simply, the immersion method is to prefabricate a circular tunnel on the ground, then dig a trench on the seabed, and sink the tunnel into the trench. Finally, the immersed tube tunnels are spliced ​​together.

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The shield tunneling method and the tunnel boring machine method use specialized machinery to advance through the geological layer or rock layer, and then workers inside the machinery splice the concrete segments into a tunnel.

The difference between the shield machine method and the boring machine method lies in the equipment used. Each of the three tunnel construction technologies has its own characteristics and advantages and disadvantages.

For example, an academician advocated the use of the burying method. The advantages of this method are that the construction difficulty is the least, the construction speed is fast, and the investment is the least.

However, it has been opposed by many people because it is very simple. This area is within the scope of the Bohai Sea Marine Reserve. There are more than 30 kinds of benthic creatures living in this area, including 8 species of annelids, 11 species of molluscs, arthropods,

There are 15 species of animals, all of which are nationally protected animals. Once the tunnel construction method is adopted, it will cause a devastating blow to these protected creatures.

This is also the reason why it was much easier to build undersea tunnels and bridges in the past than it is now. Because there was no awareness of environmental protection, animal protection and the like before, but it is different now. If you dare not pay attention, then various international

Environmental groups and animal protection groups will be in an uproar, and some countries will also cause trouble behind the scenes. The international impact will be very bad at that time, and the construction may be abandoned halfway due to the huge international public opinion, causing huge losses.

China is a responsible big country and cannot ignore it like some countries do.

Therefore, this burying method has been rejected. Of course, a detour can also be made, but the mileage of this detour will be doubled, and the project investment will also be doubled.

By then, it is estimated that even 400 billion yuan will not be able to stop it.

This time the Bohai Tunnel meeting lasted longer than before, lasting for three days. All parties had full discussions on theory and actual construction, and gradually everyone formed a consensus that the shield tunneling method and

A combination of sinking and burial methods.

After all, simply using the shield tunneling method or the tunnel boring machine method has a big drawback, that is - expensive!

For short-distance undersea tunnel construction, this gap is not very obvious. However, as the length of undersea tunnel construction becomes longer, this gap becomes more obvious. Whether it is in materials or labor, the monetary cost will increase with the length.

And gradually increase. Using this method, 250 to 300 billion is not necessarily enough. If weak strata or special circumstances are encountered, the cost will be further increased.

Moreover, the shield tunneling method and the tunnel boring machine method have many construction difficulties, and the technical requirements are much higher than those of the immersion method. For the immersion method, as long as the docking problem of the immersed tube tunnel is handled well, everything will be fine. But the shield tunneling method and

The tunnel boring machine has different laws. There are no big difficulties, but there are a lot of small technical difficulties.

For example, when using equipment to excavate a tunnel, how to ensure that the surrounding soil and rock layers do not collapse and become unstable. When the equipment relies on the thrust of the jack to push forward, how to control the total thrust of the equipment so that it does not cause the front side to collapse due to excessive thrust.

The soil moves forward and bulges due to extrusion, because the thrust force is too small, which affects the propulsion speed.

Wait, wait, there are a lot of difficulties.

Moreover, due to the different geological conditions of each sea area, these technical difficulties cannot be borrowed from other completed projects.

Finally, an academician proposed to use a combination of burying method and shield tunneling method. In places where burying method is allowed, burying method should be chosen, and in places where burying method is not allowed, shield method should be chosen. In this case, although the cost will be higher than simply

The burying method is higher, but within the acceptable range.

But this method of combining each other is not without problems. The biggest problem is the connection between the tunnel section constructed by the shield method and the tunnel section constructed by the buried method. After all, the tunnel specifications obtained by the two construction methods are different, and one is built under the seabed.

, one is placed on the seabed, how to connect it?

Detailed connection like this is not as simple as CAD drawing, it needs to be truly practical, otherwise it will be meaningless.

After an afternoon of discussion at the meeting, no one came up with a feasible solution. Even the academicians frowned and thought sadly. They also proposed some solutions, but they were theoretical, but the actual construction was not.

Very difficult, almost impossible to implement.