After ten years, my country's railway tunnel successfully crossed the huge disastrous fault zone for the first time
The builder of the "Dragon Heart Piercing Needle" in the Longmenshan Fault Zone
In the song of triumph, people shook hands tightly, and the corners of their eyes were hot.
From the Chengdu Plain at an altitude of 500 meters to the Northwest Sichuan Plateau at an altitude of 3,000 meters, they finally achieved a new crossing of the "long heart through the needle" on the fault zone.
This is the core area of the Wenchuan earthquake and the "heart" of the Longmenshan fault zone.
Builders deep underground have overcome many difficulties such as the complex geology of the high-altitude fault zone, high ground temperature, high water inrush, high toxic gas, etc., and worked hard to dig a large tunnel that can be called a miracle.
They have experienced difficulties that are rare in the world, and they are more aware of the blood, sweat and technology behind it.
After ten years of hard work, it was designed by the China Railway Second Institute and constructed by the China Railway 19th Bureau and the China Railway Fifth Bureau. The left and right holes of the Yuelongmen Tunnel of the Chengdu-Lanzhou Railway were finally completed.
The steel frame is twisted like a twist, and the temperature is transpiring like a sauna
The Longmenshan fault zone is one of the active fault zones, where the Wenchuan earthquake occurred in 2008.
On the surface, the Longmen Mountains are vast and undulating.
As for the structure in the mountainside, people are extremely lacking in information.
"The previous construction was relatively normal. In 2018, as the tunnel was drilled to the No. 3 inclined shaft in the center of the fault zone, all kinds of difficulties suddenly intensified. To use an inappropriate analogy, this complex geology is like an active ' Dragon'." said Wang Hailiang, project manager of Chenglan Railway of China Railway 19th Bureau, one of the contractors.
"How do you understand? We used to deal with the deformation of soft rock, and it was generally fine after the reinforcement was completed, but when the left hole, the flat pilot hole, and the right hole were excavated here, the hole group effect of the three holes appeared at once, and the reinforcements were also reinforced. Deformation together, the round hole becomes a flat hole, the top is collapsing, the bottom is on the top, and the front and rear are squeezing." Wang Hailiang said, "When the deformation rate is the largest, the H-shaped steel frame with a height of 20 cm and a height of 20 cm is deformed within 24 hours. Twisted and broken like a twist, like an invisible hand 'pinching sausages' in a different way."
From January to August 2018, the face of the construction work did not reach one meter, and even the Spring Festival was in emergency. The project builders racked their brains to solve this problem.
One wave has not settled, and another has risen.
There are many hot springs in the Longmen Mountains, some of which can scald boiled eggs, and the ground temperature is extremely high.
If you stand for 10 minutes, you will be sweaty, let alone work. After 20 minutes, you must go to the hole to breathe, otherwise you will collapse.
The three-arm rock drilling rig can only work with one arm. It keeps pouring water on the engine to cool it down, but the equipment engines are still "opening the pot" one by one and shutting down, and the screw of the air compressor is burning red... Thousands of sets were originally Equipment that can be used for 5 years will be scrapped in high temperature after only one or two years of use.
The project department originally thought of spraying water to cool down, and purchased 40 fog cannons to reduce smog.
Unexpectedly, spraying water mist inside the cave is more humid and hot like a steamer. Some workers lift up Wang Hailiang's shirt. For three consecutive days, a small piece of red today, a large piece of red tomorrow, and the whole back of the day the day after tomorrow. It's itchy. Heart-piercing eczema, the more you scratch the more itchy!
The project department quickly stopped spraying, re-purchased ice machines, worked more teams, shortened individual working hours, and took shift breaks and treatment.
Throughout 2018, tens of thousands of people were rotated, and the scale of more than 600 people per day was always maintained.
"It's really hard work. The team wears shorts to work. After a while, they have to hold ice cubes to cool down. 120 tons of ice are delivered every day." said Liu Guoqiang, chief engineer of the Chenglan Railway Project of China Railway 19th Bureau.
The torrents shot like arrows, and the poisonous gas lurked like poisonous snakes
There are many strange peaks and different waters in Shushan, especially the Yuelongmen Tunnel that needs to pass through the Gaochuan River.
In 2015, it was found that the normal construction water output is nearly 70,000 cubic meters per day. When drilling the blasthole, the water can spray more than 10 meters, and the explosives are flushed out as soon as they enter. .
In the rainy season, the water output is as high as 130,000 cubic meters per day, which can fill 68 standard swimming pools. In case of floods, the record is constantly refreshed.
"In the most dangerous one, the flood trapped hundreds of people in the No. 3 inclined shaft. We organized workers to row the tires to escape." Liu Guoqiang said, with fear on his face.
The fracture is accompanied by water erosion, and it is complex and unpredictable in the deep underground.
What is even more frightening is that in some crevices, invisible and intangible dangers are quietly rising.
"After opening the stratum, it was found that a large number of carbonaceous rock layers had gas attached to it. In 2018, it was identified as a high-gas tunnel. 9 cubic meters of gas gas per minute poured out of the tunnel. With the water gushing, the hydrogen sulfide gas in the water also drifted out. The two Combined, it can be poisoned at light, and exploded at worst!" Liu Guoqiang said that the Chengdu-Lanzhou Railway Company and the designer China Railway Second Institute organized to learn from everywhere, and the Sichuan Coal Industry Group sent a professional ventilation team of more than 30 people to support.
However, field studies have shown that mine ventilation methods are difficult to use directly in railway tunnels.
"The wellhead of our mine is small, and it uses negative pressure to extract the toxic and harmful gases. The railway tunnel has many excavation areas, large wellheads, and many branch lines. , originally planned to come to support for two years, but the result has been kept from 2018 until now.
From the point of view of line selection, coal-bearing strata, goafs and fault areas with high activity have been avoided as much as possible.
In particular, it avoided the epicenter of the Jiuzhaigou M7 earthquake on August 8, 2017, which confirmed the rationality of the plan.
Nonetheless, in the face of the difficult-to-reach mountainside in geological exploration, the construction encountered a number of worldwide problems, and each "blocker" tested the builders.
Technology is as furious as a god's eye, and the tunnel extends like a god's needle
The only thing that can make difficulties bow their heads is the law.
Only technology can find the law.
Difficulties are forcing people to seek productivity from technological innovation.
For the large deformation of soft rock, after 8 months of construction difficulties, the designer and the construction party kept trying and made mistakes and found the correct method: first move the leveling tunnel outwards to weaken the effect of the cave group, and then use the principle of "deepening the geology, actively Control, strengthen the bolts, cooperate with construction methods, and optimize the process", and formed the "Construction Construction Method of Two Steps with Inverted Arch (Short Steps) Rapidly Closed and Ringed", which has become one of the main popular construction methods for my country's railway construction to deal with large deformation of soft rock.
For Gao Yongshui, Shandong University, Southwest Jiaotong University and other institutions have introduced a series of domestic innovative technologies under research.
For example, the "Complex Environment Deep Engineering Disaster Simulation Test Equipment and Key Technologies and Applications" chaired by Li Shucai, an academician of the Chinese Academy of Engineering, can reveal the hydraulic environment in unexcavated rocks in advance.
After the practice of Yuelongmen Tunnel, this method is effective and won the second prize of the National Technology Invention Award in 2020.
For high ground temperature and high toxic and harmful gases, after many studies, the construction party "does the opposite" to the mine ventilation equipment, changing the exhaust air to supply air, and designing the main air path and branch air duct in combination with the operation point, with 3.4 The main fan with a radius of 100000000000000,0000000000000000000000000000000000000000000000000000 of fresh air, structurally changed the tunnel air environment.
During the research, Pan Kaifang, an old expert in his 60s, only slept for two hours for three consecutive nights. He calculated, drew, verified, and reconstructed... and finally completed this air supply project, which can be called the "Great Wall in a Cave".
The 19th Bureau of China Railway also creatively proposed "determining production based on wind", how much new wind there is and how much the amount of excavation is determined, and the scientific spirit of seeking truth from facts is permeated in construction.
In this way, one meter after another, the Yuelongmen Tunnel runs safely through the heart of the Longmenshan fault zone like a needle.
This 19.981-kilometer left line and 20.042-kilometer right line control engineering tunnel of the Chenglan Railway started construction in December 2012. The left line was completed on November 28, 2021, and the right line was completed on April 25, 2022.
Its complete penetration is the first time that a railway tunnel in my country has successfully crossed a huge catastrophic fault zone, and a wealth of geological data and construction experience in the heart of the fault zone has been obtained. It has become a great feat in the history of tunnels in the world!
This honor belongs to all the builders who paid for it.
(Reporter Xie Jiao participated in the writing: Wu Yu)