How to solve the problem of the tunnel at the same time at the same time?

On August 17, the Guinan High -speed Rail 90,000 Dashan 4 Dashan Tunnel of the Guinan High -speed Railway, located in the Maoan Maoistan Autonomous County, Guangxi successfully penetrated. At this point, the 108 tunnels of the Guinan high -speed railway across the line were all connected. The construction of the Guinan high -speed rail in construction is an important part of the main channel of the "Eight vertical and Eight Heng" high -speed railway channels to the Haikou Channel. The design speed is 350 kilometers per hour. It is expected to be opened at the end of 2023.

Guinan High -speed Railway Tunnel under the drone lens (picture source: Xinhua News Agency)

With the construction of transportation projects such as China's high -speed rail and China highway, China has become the world's most tunnel and bridge projects in the world. The kilometer ultra -long tunnel. So how do these tunnels that do more than ten kilometers and dozens of kilometers are not bad for each other?

Measurement -the key to whether the tunnel can be connected as expected

A tunnel finally achieved smoothly, which was completed by all departments of the entire tunnel project, including survey, design, construction, supervision and acceptance. It is the measurement department for controlling the position of the tunnel engineering position. Whether the tunnel can be excavated at the expected location, measurement is the core of no doubt. Generally speaking, the measurement of tunnels is divided into two aspects: plane and high -end to ensure the posture of the tunnel.

The measurement work begins at the entire project preparation stage. From then on, the survey department must provide the surrounding terrain of the corresponding lines for the road design department. This will eventually determine whether to repair the tunnel and the opening of the tunnel. When the tunnel design phase is completed, the construction phase starts, and the earthwork is not moved, and the measurement is advanced.

The construction team will first set up a measurement control network in the working area. It plays the role of connecting the national surveying and mapping control network and the surveying and mapping control point of the work area, and determines the accuracy of the measurement results within the construction area according to the structural intensity of the construction control network. To put it simply, before the formal construction, some special points need to be set up around the work area. The distribution must not only meet the rapid measurement in the work area, but also need to be affected by the construction as little as possible. These control points are measured by the national benchmark point to measure their corresponding positions. All the subsequent measurement work began (calculated) and end (test) based on these special points.

High -precision measurement is inseparable from advanced surveying and mapping tools

After setting up the construction control network, it is the corresponding construction. Like the woodworking ink line or the lines during the decoration at home, it is the work to guide the construction team to carry out construction. During the tunnel excavation process, the direction of the excavation must be indicated, and the midline and waistline of the tunnel must be calmed. This limits the boundary of the tunnel construction, which is the so -called referring to where to fight. However, due to the special environment of the tunnel, the electromagnetic wave is difficult to penetrate the thick rock wall, so the most commonly used RTK (real -time dynamic dynamic differential technology) such as GPS measurement methods cannot be used. Plane measurement and level measurement.

The whole station instrument used in the tunnel (picture source: Author)

The whole station uses the principle of lighting along the straight line. In the real work, it will be affected by the dust in the tunnel. At the same time, because the instrument operation is also completed, the various errors cannot be theoretically avoided theoretically avoided avoiding it. Essence However, through multiple measurement flat measuring computing and reasonable cloth, the wire or triangle network, plus the computing power and highly automated optical equipment that comes with the new whole station instrument, can be quickly calculated. The modern full station instrument replaced the optical disk with optoelectronic scanning disk, which automatically records and display the number of readings and display the number of readings, so that the error generated is very small, reaching an error of only a few centimeters or millimeters per kilometer.

The TBM (Tunnel Boring Machine tunnel excavator) with a wider and more efficient TBM (Tunnel Boring Machine Tunnel) is equipped with laser target bias, which ensures that engineering equipment can be traveled according to design.

What should I do if the accumulation error of ultra -long tunnel is accumulated?

Will the construction of the ultra -long tunnel accumulate with the number of kilometers to increase the error? In theory, this situation does occur, but due to the increase in length, the difficulty of engineering and the increase in construction costs are much higher than the speed of control measurement error accumulation. Therefore, it is generally selected to build a short tunnel -in the construction -that is, the way to build horizontal caves, diagonal wells, and vertical shafts in the tunnel, and decompose the long tunnel into a short tunnel of a paragraph. Although such construction plans will increase construction costs, there are also benefits such as shortening tunnel working periods and improving ventilation and drainage conditions during construction. After the tunnel is completed during the construction of the tunnel, the excavated wells can also be used as ventilation wells, fire channels, maintenance and emergency channels, etc. to enhance the safety factor of the entire tunnel.

For example, the world's longest plateau tunnel that has been built in my country, the Xining to Golmu section and the Guanjiao tunnel of the Qinghai -Tibet Railway, is 32.690 kilometers in length (the high journey of tunnel imports is 3380.75 meters, and the export high is 3324.05 meters). Due to the harsh construction conditions, in order to adapt to this kind of plateau climate, the oblique well -dividing airway technology is used, that is, 10 oblique wells to assist positive cave construction, which greatly increases the supply of air supply, meets the needs of high altitude, long -distance and multi -working surface construction needs Essence

Guanjiao Tunnel line construction schematic diagram (picture source: author)

Not only that, with the tunnel excavation process, the completed work section also needs to accept the inspection and calculation of supervision and measurement. Once it is found that there is a deviation from the design line, it will be remedied immediately. It's much tall together. Therefore, in the process of building a tunnel in modern times, no news of tunnels can not be seen at all. Once the tunnel construction will really not be right at both ends

Of course, if there is no corresponding measurement project, it is another scene. As a application of mathematics technology, measurement technology has developed extremely rapidly with the advancement of computing science and optoelectronic technology, and technology will be updated almost every 10 years.

In the early years of the last century, human beings also used Jingwei instruments to develop surveying and mapping tools for several centuries, and the efficiency and accuracy of surveying and mapping were quite low. At that time, in addition to the immature technology of the tunnel, it was also important to control the measurement accuracy to meet the requirements. Therefore, in the early line design, I would rather around the road, and it would not be designed as a tunnel. Therefore, in the first half of the last century, the exhibition lines of the railway and Panshan Highway in the highway were extremely active. And because these two forms of mountains are built in the deep valleys of the mountains, their surroundings are beautiful and majestic, and they often become an important landscape. However, with the development of bridge and tunnel technology, this form of transportation is getting less and less, but it is gradually disappearing.

Chengkun Railway Zhonglewu Show Line (picture source: Author)

In addition, when the construction of tunnels is inevitable, it can also be used by light digging and covering, or simply opening the sunroof. Among them, the more famous one is the wall -mounted road. Although the name is with a highway, it is actually a type of tunnel. Although these methods will use more soil and stones to increase the cost of construction, their correction is relatively simple and easy to operate. Use very simple and basic measurement tools to do the measurement requirements.

Although choosing not to build a tunnel can achieve direct surface observation on the surface and reduce the difficulty of construction to a certain extent, there are great limitations for the engineering project itself. In addition, the use of a tunnel only uses a straight -line method to reduce the difficulty of penetration without good measurement capabilities, and the fault tolerance rate is relatively large. During the construction of the tunnel, unilaterally hits the cave. Although the construction period is extended, there is no problem of tunnel docking. The above methods have played an important role in early road construction.

One -size -fits -handed bottom hanging wall road with both hands (picture source: Author)

China has challenged a series of impossible in infrastructure construction. Chinese engineers have been studying and breakthroughs to solve various problems, which fully shows China's strong infrastructure strength and perseverance.

Produced: Popular Science China

Author: Jingbo (Geological Engineer)

Producer: China Science Popularization Expo

The China Science Popularization Expo is the Science Popular Science Platform of the Chinese Academy of Sciences. It is sponsored by the Computer Network Information Center of the Chinese Academy of Sciences. Relying on the high -end scientific resources of the Chinese Academy of Sciences, it is committed to spreading cutting -edge scientific knowledge and providing fun science and education services.

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