What kind of "black technology" is needed to build a power station at an altitude of 3,000 meters?

In the Tibetan area of ​​Ganzi, Sichuan

2 km downstream from the confluence of the Yalong River and the Xianshui River

A world-class high earth-rock dam stands

Lianghekou Hydropower Station Dam

The average altitude is 3000 meters

The oxygen content is only 69% of that in low-altitude plains

The lowest extreme temperature in winter is -15.9℃

In addition, the dam is filled with ultra-large volume and ultra-high strength.

Configuration of construction sites, traffic roads, and mechanical equipment

and construction organization management

They all put forward very high requirements

High altitude and lack of oxygen cause significant reduction in the efficiency of manual and mechanical work

The Lianghekou Dam was built

Brought more severe challenges

Faced with complex geological environment and harsh climate

Hydropower builders have used various "black technologies" to create

Lianghekou Hydropower Station, the Plateau Pearl

——Equip the roller with a “brain” to ensure quality through intelligent rolling

The center of the dam is equivalent to the "heart". In order to prevent seepage, a protective wall, the "heart wall", must be built at the "heart". Currently, the height of the "heart wall" has exceeded 270 meters.

In order for the "core wall" to withstand the water pressure of more than 260 meters high and 10.8 billion cubic meters of reservoir capacity, rolling and compacting is one of the most critical steps. Wang Jinguo, director of the Lianghekou Construction Management Bureau of Yalong River Company, said that the "core wall" needs to be filled with 1,176 layers, and each layer needs to be rolled 10 times, and no carelessness is allowed.

Repeated rolling thousands of times is boring and tedious. Workers are always careless and confused. How to prevent wrong rolling and missed rolling to ensure the safety of the dam? We found the answer on the screen of the command center in front of the Lianghekou Hydropower Station Intelligent Dam System.

"Bump roller No. 24: speed, 2.63 km/h; offset, 40 cm; number of passes, 3..." A three-dimensional graphic is presented on the screen. Four rollers are driving on the screen, and the track of each vehicle is represented by a different color.

"The core wall rolling of traditional earth-rock dams is controlled by manually counting the number of times a plate is flipped over. The rolling trajectory can only be judged by the naked eye of the supervising engineer, and the speed is controlled by feeling. There are many subjective factors in the construction quality." Research and development personnel from the Intelligent Dam Project Department of Tianjin University introduced that the Yalong River Company and Tianjin University have jointly developed a real-time monitoring system for intelligent dams with a positioning accuracy of centimeters. It can calculate and analyze the roller's walking trajectory, vehicle speed, number of rolling times, compaction thickness, etc. in real time, and automatically alarm in real time to eliminate hidden dangers.

Not only that, in response to the difficulties in recruiting roller compactors, occupational health problems caused by low-frequency vibrations, and reduced construction efficiency caused by high cold and high altitudes, we have developed and applied intelligent unmanned roller compaction machine groups and native integrated unmanned roller compaction systems to further improve the level of intelligence in dam construction.

——“Cover the heart wall” to keep warm in winter and prevent freezing and thawing

In high-altitude areas, clay is extremely sensitive to changes in temperature and water content, and the effective construction time is only about 200 days a year. In order to complete the project well and quickly, the builders of Lianghekou are always exploring innovations:

In the cold winter, the core wall soil will freeze and melt, which is a problem that high earth-rock dams have never encountered. A researcher from the Northwest Institute of Eco-Environment and Resources of the Chinese Academy of Sciences said, "Lianghekou encounters shallow surface daily cycle frozen soil, which freezes at night and melts during the day. Moreover, after the compacted soil freezes and thaws, leakage channels will be formed, which is absolutely not allowed in engineering construction." In order to prevent the core wall from freezing, the builders will cover the core wall with a "thermal blanket" weighing dozens of tons every night, and uncover it when the temperature rises during the day to continue construction. Through the development of a fast retractor, it only takes 3 hours to cover the core wall, which is about the size of three football fields.

During the thunderstorm season, the steel wheels of the rollers were unable to compact the soil due to the mud hanging on them. “Sometimes the volume of filling was less than the volume of scraping away, and the core wall was getting lower and lower.” After trying many ways to solve the problem, the builders later introduced weather radar, adopted methods such as turtleback construction on the filling surface and rapid rotation of small warehouse surfaces, which greatly improved the construction efficiency during the rainy season…

——Apply a mask to concrete, intelligent maintenance to prevent cracking

In order to share the flood control pressure of the Yangtze River during the main flood season, Lianghekou Reservoir has reserved more than 2 billion cubic meters of flood control storage capacity. Coming from the "heart wall" construction site to the 16-meter-wide and 22-meter-high flood discharge tunnel, I felt cool.

The gray concrete on both sides of the cave was covered with white maintenance cloth, and the pipes on the top of the wall were spraying water, making the cave seem like a facial mask. When the maintenance cloth was removed, the concrete wall was as smooth as a mirror, and people could be clearly seen.

Why does concrete need such a smooth and moist "skin"?

Wang Zeguang, the project leader of the Lianghekou high slope and flood discharge cavern, revealed the answer: It turns out that the cavern has to cope with a maximum discharge of 4,076 cubic meters per second, which is the scouring force of a group of 160 trucks fully loaded with 25 tons of goods. This places extremely high demands on the concrete's abrasion resistance, and the corresponding maintenance requirements will also be very high. "During the curing period, the temperature and humidity of the concrete must be strictly controlled within the specified range, and the difference between the spraying water temperature and the concrete temperature cannot be greater than 20 degrees Celsius, otherwise there will be a risk of cracking, which is no joke." Wang Zeguang said.

It is not easy to strictly control temperature and humidity in Lianghekou, where the air humidity is low, the wind speed is high, and the daily temperature difference can reach more than 30 degrees Celsius. In order to ensure the casting of impact-resistant and wear-resistant concrete, the Lianghekou project used intelligent maintenance methods, laying pipes with embedded sensors on the concrete wall to monitor the temperature and humidity of the concrete in real time, and then intelligently adjust the spraying time and temperature. "Compared with traditional manual spraying, intelligent maintenance not only saves labor, sprays more evenly and without dead ends, but also saves nearly half of the water consumption." Wang Zeguang calculated.

—— "Sole" high slopes, intelligent sensing of tension

The complex terrain of high mountains and deep valleys determines the huge scale of the high slopes of Lianghekou Hydropower Station. The highest slope is 684 meters, which is 50 meters higher than the Shanghai Tower and ranks second in the world. How to deal with the strong water pressure and prevent the mountain from deforming?

The builders used the method of "making shoe soles" to reinforce the mountain. The densely packed red, yellow, blue and white dots on the mountain are the "needles and threads" of the "making shoe soles" - anchor cables. It is understood that the project needs to drive about 16,000 anchor cables into the mountain in total, each of which is about 70 meters long and weighs 1 ton, which is equivalent to transporting the steel used for the main structure of the entire "Bird's Nest" to a mountain with an altitude of more than 3,000 meters.

"It takes the combined efforts of thirty or forty people to carry a bundle of anchor cables, and they often have to carry them to a work surface at a vertical height of 50 to 60 meters." Cao Tingfa, an anchor cable worker from Liangshan, Sichuan, said that due to lack of oxygen, they often have to rest after walking ten meters or so. Some workers even have nosebleeds, and their shoulders are worn out when they finish the work.

The seemingly "bulky" anchor cables actually have hidden secrets. Some anchor cables are equipped with sensors, which will be able to monitor the tension of the corresponding slope range in real time and conduct intelligent monitoring in the future.

"When you open the door, you will see the mountain again"

In the Wilderness

Many builders work more than 300 days a year.

"I cover my child with a blanket only a few times, but I cover my heart with a 'warm blanket' hundreds of times."

…

Construction of Lianghekou Hydropower Station

Witnessed the world-class high earth-rock dam

Smart construction "achievements"

Also witnessed the builders

The spirit of facing challenges head-on

Determination to do good