Will building a subway have an impact on the geological structure?

In a big city like Beijing, sometimes it feels like "no car is better than a car". Because it's really miserable. Even if you take the bus, it is the same congestion, and the bus priority does have some effect, but when it comes to rush hours such as commuting, it really feels like it has little effect.

At this time, the subway became our best choice.

Living in a city like this, sometimes people who have a car will choose to take the subway, because there is no risk of traffic jams, and there is no worry about limiting numbers. Having said that, not all out-of-town cars can go to a place like Beijing, and that overpass will make your navigation crash in minutes. Therefore, for a metropolis, the subway is really a very necessary choice.

Building a subway is a project with high investment and slow investment. Generally, it is only possible to build with the strong support of the superiors, because this is no longer possible by the investment of investors alone. The construction of the subway is a huge project, and one of the most important is the excavation of tunnels.

Excavation tunnels have high requirements for site exploration, which must not only have sufficient strength of the site structure, but also be easy to excavate. It's really difficult. It's better where there is a solid enough geological structure, and you don't have to deal with it so much manually.

If the geological structure is soft, it is necessary to do artificial reinforcement treatment in the later stage.

I still remember that I used to build an underground supermarket in my house, and I wondered why the underground supermarket was usually a square or something like that, and then I heard that it was because the foundation of the underground supermarket was not so strong, and it could not be built again. Later, there were some buildings on top of the underground supermarkets that opened, and I think it may be that the construction technology and quality have improved.

It's the same with the subway. After you build a subway, there will be a large space underground, and this space will definitely not be as strong as before, no matter how it is reinforced. In addition, the operation of the subway will be accompanied by huge vibrations, which will have a cumulative impact on the surrounding geological environment and buildings at regular intervals.

But don't worry, the impact is minimal.

Influential. The reason for the influence is that for large-scale urban underground projects such as subways, it is necessary to clearly grasp the structure, type, age, and use status of the buildings along the project before construction, and evaluate the buildings before construction to determine the existing deformation of the building and the ability to resist the remaining deformation.

At the same time, it is necessary to improve the scope and extent of the impact of subway construction on buildings, and take corresponding treatment measures in time to ensure the smooth progress of the project.

The subway runs between 15 and 30 meters underground. According to the geological environment and the needs of the route, the tunnel presents a certain slope. In the design of the rail line, the principle of avoiding crossing residential buildings and high-rise buildings as much as possible was followed.

Generally speaking, in order to reduce the cost of tunnel construction, most subways will choose to use the third rail power supply mode to reduce the tunnel section, but this is not absolute. The main power supply methods of the subway are as follows:

Overhead cables. Overhead catenary (also known as catenary power supply)** power is one of the two power supply network methods commonly used in electrified railways, and it is also the only power supply mode for trolleybuses. In railway and urban rail transit systems, the overhead catenary has only one electrode of a wire, and the electric locomotive takes power through the pantograph and then flows back to the grid through the metal wheel rail.

In trolleybuses and other systems that use rubber wheels, the overhead catenary has two contact wires (referred to as contact wires) that are parallel to each other, one positive and one negative, which draw electricity through two collector poles and form a path.

There are roughly three types of suspension of overhead catenary: simple suspension, chain suspension, and rigid suspension. Among them, simple suspension and chain suspension are elastic suspensions. The corresponding overhead catenary is also called elastic catenary and rigid catenary according to the suspension type.

1. Simple suspension.

Simple suspension only wires, no bearing wires, the advantages are simple structure, low pillar height, the load of the support point is light, generally used in tunnels and other low clearance occasions. Simple suspension is also widely used in city light rail and trolleybuses. Its disadvantages are that the span is small, the suspension point has hard points, and the conductor will oscillate up and down during operation, which is not suitable for high-speed railway.

2. Chain suspension.

Chain suspension connects the conductor and the load-bearing line with suspension cables, which solves the problem of small span and hard point in simple suspension, so it is widely used in long-distance, high-speed, large-span electrified railways. In urban subways, it is expected to reach speeds of more than 120 km h if chain suspension is used.

3. Rigid suspension.

Rigid suspension is a new type of suspension in which a hard metal strip (usually a copper bar) replaces a soft wire. With the development of material science and structural mechanics, the rigid suspension takes advantage of the large contact area of the third rail power supply, and overcomes the disadvantage that the rail is too heavy to be suspended. When urban rail transit is driven from the underground route to the above-ground route, it is directly connected to the elastic suspension route seamlessly, without replacing the locomotive.

80% will not affect the foundation of the ground floor, if the building weighs more than 100 tons, the subway is 90% dangerous from the building foundation (some are relatively strong).

100% yes, just to a different degree.

will do, but this is solved underground.

I may not know much about other cities, but I am an employee of Chongqing Rail Transit, and I know more about Chongqing's rail transit.

Chongqing is a mountain city, most of which are hard granite, and it is difficult to excavate. And the intersection of the two rivers in Chongqing, accompanied by a large amount of soft mud, so in Chongqing rail transit, China's unique rail transit system straddle monorail has been built. Most of the elevated stations are used in the form of TBMs to dig hard rock.

Similarly, in Chongqing rail transit, there are many lines that need to cross both sides of the strait, such as the Caiyuanba Yangtze River Bridge in Line 3 (monorail line), the Jialing River Bridge from Niujiaotuo to Huaxin Street, and the Chaotianmen Bridge in Line 6, all of which use the existing bridge structure to add rail transit lines to the lower part. In this way, the purpose of one bridge can be used for multiple purposes, and it is necessary to avoid excavating tunnels and building new bridges.

Chongqing's terrain is undulating, there are few horizontal roads (so bicycles are sold less), and it is more complicated to repair or excavate rail lines.