China's subway is so deep, why hasn't the soil been transported out, and where did it all go?
Now all major cities have subways. Compared with buses, the speed of subways is not at the same level. And the subway is a kind of rail transportation. I wonder if you have such a question when you see the subway construction. Why don't you see the soil for the tunnel?
To answer the above questions, let us first understand the history of the subway.
When did the subway start appearing? It's an interesting story to tell, and many people think that the subway must have been invented by an engineer. However, things were unexpected. The subway was actually conceived by a British lawyer named Charles Pearson. He thought of the way to travel in the subway, but he was actually surprised. Once Charles Pearson found a mouse nest in the back wall of his house. He found a tool to kill the mouse, but the mouse ran along the hole in the wall. Very fast. I usually see nothing abnormal on the surface of the wall. It turned out that the inside was hollowed out by mice. After the failure to beat the mouse, Pierce suddenly had an idea. The mouse can run in the hole again, so why can't people? With the subsequent invention of the train, the world's first subway was built in London, England in 1863.
If you have to define the subway, it is actually a kind of tunnel rail transportation. The train is the rail transportation, and the subway is equivalent to the train running in the underground tunnel . After the establishment of the world's first subway in the United Kingdom, all countries in the world have established their own urban subways. The most famous one is the Moscow subway, which was officially completed in 1935. The most artistic subway.
What are the advantages of the subway? Where is it mainly applicable? In fact, the cost of the subway is very high, and it is not very suitable for long-distance transportation. The optimal distance of the subway is within 100km. It is not impossible if it is far, but it will consume huge manpower and material resources. Applies to cities. The advantages of the subway are also mainly in the city, because the land in the city is very precious, every inch of land is worth an inch of gold , and the top of the city is densely built. Building a subway does not need to occupy the land above the city, and the top of the subway is OK. Pedestrians and vehicles, saving land resources is an important advantage of the subway , but this advantage can only be reflected in combination with the city.
Another feature of the subway is that the travel speed is fast , because unlike on-ground traffic, you will encounter various complex traffic environments and situations. There are too many operations, and even today's subways can operate well without drivers and only need program control, so the speed of the subway will be very fast.
In special times, the subway can usually be used as an air-raid shelter and a shelter. In those days, countless urban residents in Moscow stayed in the subway tunnel, escaping those terrible war years. Today's subway still has such a function, so the subway is also a harmonious Defense closely related engineering.
How much does it cost to build a subway? The cost of subways is extremely expensive to the outside world. In some cities, the price of a kilometer of subways is 800 to 1000 million yuan. Although the cost of the subway is very expensive, the service life of the subway is very long, and the maintenance in the later stage is relatively simple. Because of the large flow of people in the city, the cost of building a subway can be recovered in the next ten years, and it can be used in the later period. For a long time, take the Moscow subway as an example. It has been in use for more than 80 years. It is still in use after simple maintenance and upgrades. It is no exaggeration to say that, except for serious geological disasters, the life of a subway is at least four or five hundred years. , of course, in the process, people have to constantly upgrade and transform it.
So how is the subway built? There is a special machine for building the subway, called a shield machine . This is a large-scale tunneling tool. China can already produce large-scale shield machines. It has been suppressed and blocked by foreign countries. In recent years, the tonnage of our shield machines has been increasing, and the diameter has also broken the world record . When building a subway, it is necessary to build shafts and crossways. The shield machine is a horizontal car to drill through the tunnel, and the shaft is dug directly from the top to the bottom, which can be understood as the patio of the tunnel.
Where did the dirt go when the tunnel was built? I have never seen muck trucks when building the subway. In fact, it is not that there are no muck trucks to transport earth, but they are far apart, and different shield machines have different principles when digging tunnels. Some use conveyor belts. When transporting dry soil, some directly pour water into the soil wall, and then the shield machine drill bit breaks the soil or rock, mixes it with water and extracts it through a pipe. This kind of shield machine requires high technical content, especially for pumping. The mud machine, and the ratio of water and soil