For some sections of the permafrost that are slightly severe, the method of using rubble roadbed to build the railway is not very applicable, because the air convection of the rubble may not be able to take away the heat in the permafrost. Pen & Fun & Pavilion www.biquge.info

After introducing the first method, Lin Xiaoyong continued to speak: "For the second type of permafrost, it is still built in the way of roadbed, which is called hot rod roadbed!" ”

"The so-called hot rod roadbed is to insert a hot rod into the frozen soil, in which the upper part of the hot rod is equipped with a heat sink (exothermic section), and the lower part of the hot rod is directly buried in the frozen soil (endothermic section), the middle of the hot rod is the adiabatic section, and the hot rod is equipped with liquid ammonia, which is the composition of the hot rod." Lin Xiaoyong said this, paused, and continued to explain: "Liquid ammonia, its characteristic is that it will be converted into gas when it absorbs heat, and it will turn into liquid again when it is cold. ”

"Because in the plateau area of the Tianlu route, the ambient temperature is lower than the temperature of the permafrost layer around the endothermic section of the hot rod for a considerable period of time, and the liquid ammonia in the hot rod absorbs the heat in the surrounding soil and evaporates into gas; Driven by the pressure difference in the pipe, the steam flows upwards to the upper part of the hot rod along the central channel of the hot rod, and after encountering the colder pipe wall, it condenses into a liquid, and under the action of gravity, it flows along the pipe wall to the endothermic section and continues to evaporate, so repeatedly, when it is cold, the heat in the soil is brought out through the hot rod, so as to ensure that the temperature in the soil will not rise. Lin Xiaoyong said.

Over time, when the ambient temperature drops to a very low level, the heat in the soil is also very low, and the frozen soil will be more compacted and will not be deformed.

In this way, the effect of heat transfer is achieved, so that the temperature in the soil does not become too high, resulting in unstable frozen soil.

Lin Xiaoyong continued: "For summer, because the hot rod is one-way conduction, it will not transmit the heat in the atmosphere to the permafrost through the hot rod, and in winter, a large amount of cold energy is stored in the permafrost, which will not thaw the permafrost in summer, forming an artificial permafrost, thus ensuring the stability of the roadbed. ”

For the hot rod roadbed, there are a lot of applications in the day route, but compared with the rubble roadbed, it is still a lot less, after all, the cost of this aspect is higher than the rubble roadbed.

In fact, the hot rod roadbed is the use of the principle of air conditioning, Shu Cheng even wondered if this method was Liu Lao through his own words, associated with this method, which is indeed possible.

Since the last time he met Liu Lao and Mr. Ouyang, Shu Cheng had contacted Liu Lao a few times later, and more or less mentioned Shu Cheng's conjecture about frozen soil.

Before Shucheng came to the route, Shucheng and Liu Lao also contacted once, when Liu Lao heard that Shucheng came to build the route, he was extremely happy, and said that after a while, he would go to the route of the day to carry out the construction of the test section of the roadbed.

For the solution of the plateau permafrost subgrade, in the research stage, there are not only three methods: rubble, ventilation pipe and hot rod, such as laying thermal insulation, that is, laying polystyrene and other thermal insulation materials on the subgrade, as well as awnings.

The function of these two methods is to isolate heat, ensure the stability of the frozen soil, prevent heat from entering the frozen soil, and prevent the roadbed from being unstable.

However, really put into practical application, have their own defects, all aspects are not as good as the rubble roadbed and hot rod roadbed, therefore, in the day route, is not used.

Through Lin Xiaoyong's explanation, everyone in the conference room at least generally understood the two solutions to the frozen soil roadbed, so that after going back, others asked and didn't know anything.

Finally, Lin Xiaoyong said: "For the third type, it is specially aimed at areas with thick permafrost, severe permafrost, and swampy areas, and during construction, it is generally used to lead the way with bridges. ”

In the case of swampy areas, it was clearly not appropriate to build a roadbed on it, so the construction of bridges had to be used.

When Lin Xiaoyong said this, Shu Cheng answered: "In fact, on the heavenly route, these three methods are the most common to deal with the problem of frozen soil. ”

When it comes to leading the road with bridges, many people will definitely think that the most difficult permafrost areas can be solved by bridges, why not use bridges for the roadbed of the permafrost section, so that it does not have to be so cumbersome.

In fact, researchers have also considered this problem, first of all, the railway is a century-old plan, to ensure that the railway runs for a hundred years, it is extremely difficult, how to ensure the stability of the railway, is the most critical.

For bridges, even if the concrete used is strong durability concrete, it will still be corroded and invaded by the environment, and the longer the time, the greater the danger, plus a hundred years, no one knows whether the surrounding soil and air elements will change.

Once the change has an impact on the bridge, it is absolutely fatal.

However, the roadbed is different, especially the use of rubble roadbed and hot rod roadbed, so that the frozen soil becomes more compact, the roadbed is more stable, and there is no danger of bridge corrosion.

Therefore, the researchers decided to use the roadbed section and solve the problem of using the roadbed instead of using the bridge.

Another point is also from the cost of consideration, although the country has money, but also to moderation, Jinqiao Yindong, it can be seen how much the bridge construction costs.

In order to reduce the investment budget, it is obviously more cost-effective to replace bridges with roadbeds!

"In the case of bridges, the most difficult part is the construction of the pile foundation, because there is a permafrost layer underneath the ground, which is, to put it bluntly, ice. In the process of pile foundation construction, concrete should be poured, and when the concrete is solidified, heat dissipation is required, and once the heat is dissipated, it will have an impact on the surrounding permafrost layer. "Shucheng Road.

When pouring ordinary concrete, the heat of hydration emits a lot of heat, like some large-volume concrete pouring, small plastic pipes should be buried in the concrete, and then water should be poured into the plastic pipes to cool down.

The construction of pile foundations in the plateau permafrost area is drilled directly into the permafrost layer, and the heat emitted when pouring concrete will melt the ice around the permafrost.

When the ice melts, the pile foundation will sink, and once the pile foundation sinks, the piers and bridges above the pile foundation will also sink, which will threaten the safety of the railway.

Therefore, how to solve this problem is particularly important!

"In order to solve the heat of hydration emitted when the concrete is solidified, we must make a fuss on the concrete, and control the temperature of the concrete at about 5 degrees Celsius when pouring concrete, so as to ensure that the permafrost layer will not be affected by the heat of hydration when the concrete is solidified during the pile foundation pouring process." Shucheng Road.

In fact, Shucheng knew this problem as soon as he entered the site, which is one of the reasons why Yao Gongjun, the commander of the construction headquarters, insisted on asking each project department to build its own mixing plant.

Each project department is in a different area, so the concrete requirements used are different.

For example, the first and second parts, within the scope of their construction, there is no plateau frozen soil, so for the concrete used by their project department, there is no need to go through these complicated processes.

It is only necessary to use concrete with high durability, and when building a mixing plant, it can be built according to the ordinary mixing plant on the plateau.

For the mixing plant in the plateau area, it must be different from the plain area, after all, the plateau area, need to consider the anti-freezing and other factors.

In winter, the freezing of pipelines is much worse than in most parts of the north.

Starting from the third department, that is, the project department under the jurisdiction of Shucheng, there is frozen soil, so the requirements for the construction of the mixing plant are higher.

How to reduce the temperature of the concrete during the mixing process is particularly important.

This is also a problem that Shucheng needs to consider in the process of building a mixing plant.

Since entering the Heavenly Route, not to mention the construction that has not yet begun, even the temporary construction of the station, has become more difficult.

Because you have no idea what unexpected things will happen during the construction process in such a deserted and populated place.

In order to educate the staff of the project department about permafrost-related matters, the meeting lasted for two hours.

On the whole, the effect is still good, at least most people still understand it.

After the meeting, Shu Cheng went straight back to the dormitory.

"Manager Shu, when will the construction team of the resident construction enter the site?" Lin Xiaoyong asked after entering the door.

"Cai Mao will come over tomorrow, and for the construction team of the steel processing plant, I will also let them enter the site these days." Shucheng Road.

For the construction of the station and the steel processing plant, Shucheng directly let Cai Mao and Liu Papi do it.

Because Cai Mao was more careful in his work, he asked the other party to build the construction of the station, while Liu Papi was to build a steel processing plant.

"The Land Bureau allowed the construction?" Lin Xiaoyong asked.

Although the place chosen by Shucheng is the barren Gobi, it still has to be filed with the Land Bureau and hand over some of the money.

If you don't use these places, the Land Bureau won't take care of anything, but once you use it, it will cost money, and it's not that Shucheng wants to build the project department, and people agree.

In fact, many things are handled by Shu Cheng usually, otherwise, there is no way to move forward.

Even if the land occupied by the Tianqi route still has to be recorded, but this matter has nothing to do with the project department, and the owners and the construction headquarters have already done these things.

"Yesterday, I went to Mr. Yao and I, and it has been approved, so I waited for Cai Mao and several other team members to go to Golmud and arrange to enter the venue." Shucheng Road

In order to construct the sky route, Cai Mao can be said to have spent a lot of money, and also purchased a rotary drilling drill of more than 2 million yuan, ready to be transported to the day route for pile foundation construction.

Because the unit price of pile foundation construction on the day route is scary!

In the plain area, the rotary drilling drill drills into a one-meter pile foundation, at most 300 yuan before tax, and the excavator and crane have to go out by themselves.

But the pile foundation construction of the day route, drilling into one meter, but it is more than 600 pieces, the excavator and crane used in the construction are all from the project department, and the price can be said to be very high.

Of course, this has a lot to do with the harsh construction environment and difficult construction in the plateau area.

This also led to the fact that even Cai Mao couldn't help but want a piece of the pie.

ps: These two chapters are more difficult to write, I wrote it for six or seven hours, and it took me an afternoon and a night to finish, in fact, this is how the Qinghai-Tibet Railway solves the problem of frozen soil, and how to control it in the future, I will write it in the next book. (To be continued.) )