The scene commentary of the successful completion of the wind-volcano tunnel?

● The highest tunnel in the world, with an altitude of 4,95 meters and a total length of 1,338 meters, is extremely cold, low pressure, lack of oxygen, snowstorm, lightning and sandstorm, all of which are daunting.

● Soil-bearing ice layer, shallow buried stratum, hot melt geology and rich frozen soil are all "world-class" problems one after another. At 2 pm on July 24th, our reporter Zhang Jiankui said goodbye to the caravan and continued to drive south. An hour later, Master Huang, who was driving, told us that he had entered the no-man's land of wind and volcano. At 3: 5, we arrived at the Qinghai-Tibet Railway Headquarters of China Railway No.2 Bureau, which is a simple yard built by No.2 Bureau itself. The leaders here all went to the construction site, and a comrade in the office received us.

In the late July season, in most parts of the mainland, it can reach above 3℃ during the day, but the rooms here are still heated. Comrades in the office told us that the annual average temperature here is below -7℃, and now the temperature at night is 4-5 degrees below zero. Just as we were inhaling oxygen and listening to the comrades in the office introducing the situation, the weather suddenly changed outside. Looking through the window, the sand suddenly blew, the flying clouds galloped, accompanied by thunderous thunder.

"It seems that the rain here will come as soon as it is said."

"There is a strong wind of magnitude 6 or 7 outside now, mostly it thunders and doesn't rain, but it snows if it rains!"

"hey, it's snowing? Isn't this six In the snow? "

"Yes, snow and hail are the most common here in June and July, but they don't last long."

Sure enough, in a short time, the outdoor wind stopped, and nothing rained today.

No.2 Bureau undertook the seventh bid section of Qinghai-Tibet Railway, with a total length of 36.2km and an average elevation of 4,7m in the "no man's land" of Hoh Xil. The natural environment is harsh, the ecological environment is fragile and the construction conditions are extremely difficult. This section is mostly permafrost region with thick permafrost layer, and the lowest temperature in winter reaches -4℃.

"In the snow in June, ice in July, the four seasons can't be distinguished" is a true portrayal of the climate conditions here. The oxygen content in the air is less than 5%, and the partial pressure of oxygen is only 1.87 kPa, which is lower than the limit value of human survival of 11 kPa. It is a real "life forbidden zone".

under such conditions, the steel men in the 2th Bureau have overcome the international technical problems and created a miracle of railway construction in the world, that is, the tunnel with the highest altitude in the world-the Fenghuoshan Tunnel.

at 5: 2 p.m., under the guidance of the comrades of the 2th Bureau, we decided to go to the site of Fenghuoshan Tunnel to experience it on the spot.

along the way, stories about the "wind-volcano tunnel" drew us back to the deadly fight that lasted for 365 days.

On October 18th, 21, the wind volcano under the blue sky and white clouds was particularly charming. The construction site of Fenghuoshan Tunnel is full of colorful flags, and 2 employees are wearing orange youth commando uniforms, and they are busy nervously on the construction site ... Dozens of large-scale construction machinery are waiting. A fierce battle and a war of science and technology are on the verge. At 11: 3 in the morning, with an order, crisp explosions sounded one after another, and white smoke drifted into the blue sky.

After a burst of blasting, the people present were stunned by the scene before them: almost all of these blasted waste slag were crystal clear ice cubes, shining with cold light under the sunlight. This is what tunnel experts at home and abroad call the "soil-bearing ice layer" of disastrous geology, and the soil content in the ice is less than 2%. Wind volcano, this Millennium iceberg finally showed its ferocious face. This kind of geology has always been regarded as a "forbidden zone" for tunnel construction. In the face of this world-class construction problem, the scientific and technological research team headed by the chief engineer and commander of the 2 th Bureau all rushed to the now tense support work, and the commandos quickly rushed to the tunnel face, and the shotcreters picked up the concrete nozzles, and the anchors picked up the air guns and hammers ... Everything was going on nervously and orderly. After more than four hours of intense fighting, the support construction was completely completed and the first round of preliminary victory was achieved. Subsequently, after several rounds of excavation and support construction, a set of experience in smooth blasting of frozen rock, shotcreting and support of cave body was explored, the construction scheme and plan were optimized, and the construction scheme of "short footage, quick closure, strict temperature control and strong support" was determined. This scheme quickly worked in the construction, and finally broke through the problem of soil-containing ice layer in one fell swoop. At the same time, it also broke a new path for the follow-up construction.

a wind volcano that no one has ever conquered will not bow easily. The newly supported 15-square-meter thermal insulation greenhouse was torn apart by the strong wind overnight; In the newly-built generator room, the iron tiles on the roof were missing the next morning; It was a clear sky in Wan Li just now, and in a blink of an eye, the dark clouds were overwhelming, and the hail the size of peanuts was smashed over ... Strong winds, snowstorms and lack of oxygen launched a continuous attack on the builders. With the continuous extension of Fenghuoshan tunnel, the construction is becoming more and more difficult. The air in the cave is getting thinner and thinner, and lack of oxygen makes everyone feel chest tightness and shortness of breath, headache, leg weakness and purple lips. It used to take only two people to carry out the operation of each typhoon gun, but now it takes four people to hold it. The shift used to be four hours, but now it must be changed in two hours. Everyone knows in their hearts that if they work in a windy volcano, they will overdraw their lives and even face the danger of death.

Wind volcano always affects the hearts of units and leaders at all levels. Sun Yongfu, deputy head of the National Leading Group for the Construction of Qinghai-Tibet Railway and Vice Minister of the Ministry of Railways, visited the Fenghuoshan Tunnel many times and encouraged the 2th Bureau to "rely on science and technology to fight the plateau and build the world's first high tunnel". Qinghai Sheng Xizang Autonomous Region People's Government sent a condolence group and sent condolences; The leaders of China Railway Construction Corporation also visited the workers in Fenghuoshan first and then.

In November, 21, the 2th Bureau, together with relevant researchers from University of Science and Technology Beijing, developed and built a large-scale oxygen station at high altitude in Fenghuoshan Tunnel, installed an oxygen transmission pipeline, and delivered oxygen directly to the tunnel face, thus realizing diffuse oxygen supply throughout the tunnel. At the same time, an oxygen bar car is installed in the tunnel, so employees can sit in the oxygen bar car to fully absorb oxygen and relieve fatigue.

overcoming the problem of hypoxia has greatly improved the construction environment and effectively guaranteed the physical and mental health of employees. With oxygen, everyone's confidence in conquering wind volcanoes is more sufficient and their energy is greater.

If it is difficult to construct the wind-volcano tunnel, it is difficult to lack oxygen in the cold and frozen soil on the plateau, then the 296-meter-long shallow buried section is enough to make people tremble with fear.

after the tunnel entrance is excavated for 222 meters, it will enter the shallow buried section for construction. Among them, there are more than 6 meters of overburden within 8 meters, and the geology of this section is mudstone fully weathered layer, and the range of 2.5 meters in the vault is full of ice and frozen soil.

At that time, the surrounding rock temperature was between 2 and 5 degrees Celsius. At this time, the fissure ice began to melt and formed a melting circle. The melted mud fell on the helmet and crackled, and everyone's mood was extremely heavy. If the melting circle is further expanded and the support can't keep up, it is very likely to cause a landslide. The real test of life and death began. Ren Shaoqiang, chief engineer of the headquarters, led engineers and technicians to continuously test the temperature of the cave and monitor the surrounding rock, adjust the temperature in the cave at any time and observe the temperature changes; The commander Kuang Chengming led the research team to study how to safely pass the construction scheme of "shallow buried section". After three days and nights of experimental temperature change measurement and control, the research team got the first-hand information and basically grasped the temperature changes of various parts in the cave at different times. Based on this, the construction scheme of "weak blasting, short footage, strict temperature control, strong support and reserved core soil" was formulated. After nearly 6 days of experimental construction, the "shallow buried section" finally passed safely and the construction progress was driven.

during the construction, technicians and workers found that the geology, such as saturated frozen soil, primitive glaciers and fractured ice, has the property of hot melting. The main factor affecting the safety of tunnel construction is ice soil, but temperature plays a key role and is the fuse to detonate frozen soil.

in order to eliminate the obstacle of "temperature", the research team launched a tenacious contest with "temperature".

through continuous practice and exploration, we all realize that the key to control the temperature is to control the temperature during excavation, support, formwork entry, curing and mixing. At the beginning, people used stoves to heat the cave, which not only caused the temperature to rise slowly, but also caused air pollution in the cave, which affected the health of employees. Later, the heater was used to increase the temperature, but the effect was still not ideal. Can an air conditioner be used to control the temperature in the tunnel? Some people put forward this bold idea, but at present there is no air conditioner with such high power in China. What should we do? After consulting relevant experts and demonstrating in many ways, the 2 th Bureau and Shijiazhuang Railway Institute jointly developed a special air-conditioning ventilator for large tunnels. When driving, use air-conditioning ventilator to send the required cold air to the tunnel face to ensure that the tunnel face temperature is controlled between plus and minus 5 degrees Celsius to meet the driving needs. When supporting the lining, send the temperature that is neither too high nor too low to the supporting working face to ensure the appropriate temperature for supporting and lining. In order to solve the temperature of concrete entering the mold, two large steam boilers were installed at the entrance of the cave for 24-hour central heating, and two heat preservation greenhouses were built. All the mixing station, sand and gravel and construction water were put into the heat preservation greenhouses, so that the temperature of the mixing station was always above 1 degrees Celsius and the temperature of concrete entering the mold was not lower than 5 degrees Celsius.

after controlling the temperature of concrete entering the mold, new problems appear again. This is the control of curing temperature of concrete. In this regard, engineers and technicians and workers have not paid less attention. In order to ensure the curing temperature after lining, after repeated practice, the heating pipe is finally used to transport the required heat and temperature, and the steam curing method is adopted to solve the problem of concrete curing after lining. By adopting different methods, all kinds of temperature problems in construction are solved.

It stands to reason that the problem of lack of oxygen in the construction has been solved, and the construction temperature in the tunnel has been well controlled, so the tunnel construction can be carried out smoothly. However, "rich frozen soil" appeared again, and the construction was blocked again.

The so-called "rich frozen soil" refers to the geology in which frozen soil contains more ice bodies. During the construction, it is found that the main characteristics of "rich frozen soil" are similar to those of "soil-containing ice layer" and are also very sensitive to temperature. In order to overcome the technical problem of "rich frozen soil" as soon as possible, Ren Shaoqiang, the chief engineer, led the research team to challenge "rich frozen soil" again. Through the test, we found that the main technical difficulty of "rich frozen soil" lies in how to improve the blasting method and how to quickly improve the strength of concrete support. In order to solve these problems, the research team decided to adjust the working procedure and adopt the "tube blasting method". After blasting, cold air is quickly delivered to the tunnel face to prevent the "rich frozen soil" from melting in heat; At the same time, the "super-advanced" support is implemented to ensure the stability of surrounding rock. Careful organization and scientific construction finally subdued the disastrous geology of "rich frozen soil".

on September 12, 22, the tunnel excavation broke through the 1-meter mark, and the double tunnel openings achieved a new construction record of over 1 meters.

Everyone has suffered a lot for the tunnel of Fenghuo volcano. Due to the severe hypoxia in Fenghuo volcano, 1% of the workers have altitude sickness in different degrees, and they can't eat or sleep. Everyone's weight has dropped by 12 kilograms on average, and more than 3 kilograms.

history will always remember this day, October 19th, 22. On this day, leaders and experts at all levels, such as the Ministry of Railways and Xizang Autonomous Region, Qinghai Province, and dozens of news media, such as Xinhua News Agency and CCTV, focused their attention on Feng Volcano. As Lu Chunfang, commander-in-chief of Qinghai-Tibet Railway Construction, started the last button, in an instant, firecrackers, applause and cheers turned the volcano into a sea of joy.

at 5: 5, we arrived at the fenghuoshan tunnel. The words "Wind Volcano Tunnel" at the top of the cave mouth are very striking. It is a little calm here because there is no rumbling guns and roaring machinery. A long track extends into the deep tunnel, and there are fading lights in the depths. By the light, you can see someone working on the wall of the cave inside, and from time to time, a hopper car loaded with cement slides slowly along the track to the hole.

The comrade who led us said that there is less oxygen in it, so you can't go in. Just leave a souvenir at the tunnel entrance!