With the 10 million project funds allocated by the construction headquarters in place, on August 25, the test section of the Fengmingshan Tunnel officially entered the construction stage. Pen? Interesting? Pavilion wWw. ｂiquge。 ｉｎfo

In the morning, Yao Gongjun, commander of the bureau headquarters, Kong Zhijin, chief engineer and others, all came to the scene and carried out a grand groundbreaking ceremony at the mouth of the tunnel on the south side of Fengming Mountain.

Of course, this groundbreaking ceremony cannot be compared with the groundbreaking ceremony of the heavenly route, but relatively speaking, it is already very grand.

Most of the personnel of the Shucheng project department participated in the groundbreaking ceremony.

After the ceremony, the formal construction phase begins.

The first step was to remove the vegetation that covered the mouth of the Fengmingshan Tunnel.

If it is in the plain area, these grass vegetation can be directly dug up with an excavator and transported away.

But this cannot be done here, because it is a plateau area, and the ecology is fragile, and these vegetation must be cleared out according to the requirements of the construction headquarters, and then placed on the side of the tunnel, protected in a special place, and used when it is restored in the future.

In the plateau area, it is not easy for many vegetation to survive, in order to protect the ecological environment, every construction team must establish the idea of protecting the environment.

Some people may think that this is a complete overkill, but when you have experienced the life of the plateau yourself, you will know how important environmental protection is to the plateau area.

Since the excavator could not be used, it could only be cleaned by hand and some hand tools, and then transported to the side with a forklift to protect it.

This process is quite slow, originally the excavator worked for an hour, and the manual work required a whole morning.

So after the groundbreaking ceremony, Yao Gongjun and others left the site after watching the construction for a while.

Shu Cheng also left the site half an hour later, after all, the site has begun normal construction, as a project manager, there is no need to stay at the site for a long time, otherwise why do you want the deputy manager in charge of the site.

Now the two sides of the Fengmingshan Tunnel are being constructed to the middle at the same time, which are the construction teams of Zhao Ritian and Qiao Ganglie.

As for the deputy managers, they are Wu Batian and Yan Yuyang, who are in charge of the construction on one side, and Chang Kai is temporarily in charge of the affairs in the project department.

In less than five o'clock in the afternoon, Wu Batian called Shucheng.

"Manager Shu, this job can't be done!" Wu Batian was a little angry.

"What's going on, you say slowly." Shu Cheng said calmly.

For the construction of the Fengmingshan tunnel, there will be difficulties, that is a normal thing, if there is no problem, then there is no need to carry out the construction of the test section, direct large-scale excavation is not enough.

"The excavator and the forklift cooperated, but they couldn't dig it, and they dug up part of the frozen soil on the surface, and if they went inside, they couldn't dig it at all, it was too hard!" Wu Batian explained.

Because he didn't understand the situation at the scene, Shu Cheng couldn't talk nonsense, so he had to say: "I'll come to the construction site immediately!" ”

Since there are difficulties on the construction site, which have affected the construction, Shucheng must go on a trip to see if there is a solution.

When Shu Cheng arrived at the site, construction had stopped, and an excavator and a 50 forklift were parked on one side.

Seeing Shucheng's car stopped, Lao Peng and Wu Batian, the foremen of Zhao Ritian's construction team, all came over.

"Manager Shu!" The two greeted Shu Cheng.

"Well, what's going on, is the geology very hard?" Shu Cheng asked.

"The power that the excavator can exert is too small, the strength is insufficient, and the perennial frozen soil area here, many of which are underground ice, are very solid, and the excavator cannot be constructed without loosening." Wu Batian explained, and together with Shucheng, he walked to the construction office at the mouth of the tunnel.

For Wu Batian's words, Shu Cheng nodded, for the power problem, in fact, under normal circumstances, the excavator can be dug completely, but because it is a plateau area and high altitude, the machinery caused by the oil combustion is not sufficient, the power is greatly reduced, and the efficiency is not as good as usual.

In the tunnel plan, when the preparation began, there was no blasting, because it was considered that blasting with frozen soil may cause instability in the mountain.

Later, when the technical department submitted the plan to the construction headquarters, it was rejected, saying that it would not work at all without the blasting method.

Because the technical members of the construction headquarters have quite rich experience in plateau construction, they know more about permafrost than Shucheng and others.

Now a construction, the problem is immediately exposed, the excavator can not dig at all, this is still summer, the strength of the frozen soil is somewhat reduced, once it is winter, it is even more impossible to construct.

Even machinery can't be used, and if you use manual labor, the progress will be even slower.

The blasting scheme given by the construction headquarters is the microseismic loose blasting technology of shallow space and deep hole steps, and the KBW frost-resistant and waterproof ******** layered charge is selected, and the non-electric millisecond **** detonation is selected.

Because the permafrost contains a lot of underground ice, once the vibration is too great, the ice layer will crack, and it is easy to collapse in danger, and ordinary blasting technology cannot be constructed at all.

The microseismic loosening blasting technology can calculate the range of vibration influence during the explosion through the amount of charge, so as to control the disturbance to the mountain.

Once the frozen soil is loosened, it is much easier to excavate it mechanically.

"It seems that you still have to use blasting, but fortunately there is something in the plan, otherwise it will be troublesome!" Shucheng Road.

Construction blasting must be filed with the relevant state departments, otherwise, you will not be able to buy explosives and ****.

Especially in cities like Golmud, the control of this aspect is stricter than that of other places in the country.

The approval procedures, the whole set of down, it took more than ten days at that time, it was already very fast, as long as it was because of the members of the construction headquarters who helped dredge the relationship.

If the blasting method was not added at that time, and if you want to continue to join it now, it will be difficult to stop work for more than half a month before you can continue construction.

When the construction started, Shucheng did not arrange the construction with explosives in order to save trouble, and now it seems that this matter cannot be saved.

"Well, you don't need to blast to loosen the frozen soil first, you can't dig at all!" Wu Batian said, and continued: "Even if I don't know if this kind of blasting will affect the entire mountain. ”

"Manager Wu, don't worry, the micro-seismic loosening blasting method, I have also used it several times in the dry tunnel, and the arc of his vibration is not large, only on the frozen soil in a certain range, which has a loose impact, and has a negligible impact on other frozen soil and mountains.

Zhao Ritian's on-site foreman Lao Peng said.

"Lao Peng, have you used it before?" Shu Cheng asked.

"I have used it in urban underground engineering, because of the impact on the structure above the ground, in many places, microseismic loosening blasting technology is used." Old Peng Dao.

In the city, if you use ordinary blasting, one shot goes down, the ground will be stuffed, and the buildings on the ground will be affected, and there are many potential safety hazards in ordinary blasting methods.

Therefore, most of the successful underground parts of rail transit are loosened by microseismic blasting, and then the soil is loosened before being transported by excavators or forklifts.

"Well, when the time comes, test it, it seems that the revision suggestions given by the construction headquarters are still very well considered." Shucheng Road.

"It is indeed very thorough, which also shows that there are people in the construction finger who know a lot about frozen soil construction." Wu Batiandao.

At this time, Shucheng had already come to the mouth of the excavated tunnel.

After coming forward to watch, Shu Cheng found that the surface seasonal melt layer can be dug up with an excavator.

The so-called surface seasonal melting layer is that in winter, when the temperature drops, this part of the mountain will freeze, and in summer, this part of the mountain will be melted again.

As for the permafrost layer (containing soil and ice) inside the surface seasonal thaw layer, the excavator is more difficult.

I don't know if it's because the excavator is too small, every time I dig it, I can only make a short progress, and the effect is not very ideal.

At this moment, Shu Cheng felt a drop of water fall on his face, and when he looked up, his brows couldn't help frowning.

"How does it tick and tick the leak? Where does this water come from? Shu Cheng wondered.

But as soon as Shu Cheng finished speaking, he realized something.

When Wu Batian and Lao Peng heard this, they also looked up, only to see that the mountain above their heads was originally a seasonal melting layer, which contained ice crystals, but now it is actually beginning to melt!

Seeing this phenomenon, a word suddenly popped up in Shu Cheng's mind, hot melting phenomenon!

The so-called hot melting phenomenon refers to the phenomenon of partial melting of underground ice due to changes in thermal conditions in the ice edge area, forming caves, surface subsidence and collapse.

Obviously, after the original mountain vegetation was cleared in the Fengming Mountain Tunnel, the temperature of the mountain changed greatly due to the loss of vegetation protection, resulting in the phenomenon of heat melting.

Once the hot melt phenomenon is not dealt with in time, it is very likely that a large-scale collapse accident will occur.

After all, it is still summer in Golmud, and the sun temperature is high during the day, and the mountains that have lost the protection of vegetation are exposed to the sun, and the ice in the mountains will melt after being heated, which also forms the phenomenon of heat melting.

Once the hot thaw phenomenon is serious, the strength of the soil will drop sharply, and the soil will become a flowing state, which is the hot thaw subsidence often encountered in frozen soil!

"Arrange personnel first, cover the excavated part with thermal insulation measures, and don't continue to let him melt, otherwise a large-scale collapse will occur, and then it will be troublesome!" Shu Cheng immediately arranged.

Wu Batian and Lao Peng are also aware of this problem, and now the only way to do this is to cover it first and isolate the sunlight, so that the heat is temporarily isolated, so that the phenomenon of hot melting will not continue to occur.

Of course, because the mountain vegetation is cleared, there will still be some heat melting.

Shucheng did not expect that on the first day of construction of the Fengmingshan Tunnel, he encountered this kind of problem, and before that, there was relatively little consideration for this aspect, but once the construction was completed, these problems were exposed.

The phenomenon of hot melting must be solved, and before it is solved, if the construction continues, the danger is too great, and Shucheng is still not at ease.

"Manager Shu, there is no quilt or any insulation material on site!" Due to the suddenness of the incident, these insulation materials were not prepared at the scene.

"First cover it with the turf that you just cleared, and in addition, notify the material department to immediately transport the quilt and other surrounding materials to the construction site!" Shu Cheng arranged.

Fortunately, the excavation is less than two meters deep, and it is excavated in layers, and the excavation area is also very small, so it is only a small range of hot melting. (To be continued.) )