Introduction: After more than 2 years, the construction of China's first and only bobsleigh track that meets the standards of the Winter Olympics was completed. It can be called a perfect "snow dragon", but the terrain conditions of the construction are not very "perfect". What difficulties and challenges has it experienced, and how have we Chinese engineers and workers successfully overcome it?
At the foot of Xiaohaituo Mountain, at an altitude of 2,198 meters, among the rolling pine forests of the mountains, lies a soaring dragon. It is 1975 meters long and has a drop of 121 meters, which is equivalent to 45 stories high. This is the world's unique "snow dragon" - Yanqing National Bobsleigh Center.
On February 10, the snowmobile race began its schedule at "Snow Dragon", and the Chinese snow team also made its debut at the Winter Olympics and stood on the track. During the race, athletes will go through a 360-degree roundabout, as well as 15 other different corners. This is not only the only 360° slalom in the world, but it has also reached the international top level in terms of the number of corners, track length and race difficulty.
National Bobsleigh Center Drone Aerial Photography @ Visual China
Not perfect terrain conditions
It looks like a perfect "Snow Dragon", but it has imperfect terrain conditions. The rest of the world's tracks are located on the north slope, and only the "Snow Dragon" is "forced" to become the only track on the south slope because the north slope is too steep.
Although the "Snow Dragon" seems to be strong and stable, it is actually in a thick collapsing loess soil layer, which may be washed away by small earthquakes and mudslides at any time. Therefore, under the stone slope in front of the race track in the departure area and under the barbed wire fence blocking the stone slope are three deep retaining walls. In addition, the "Snow Dragon" is located on the ridge, and there are steep walls on the east and west sides, which is very unfavorable to the transportation of construction equipment and equipment. All equipment and equipment were transported up the hill by helicopter and the mule and horse teams of the farmers. The excavator did not dare to turn off the fire for 24 hours at the top of the mountain, because it was more than thirty degrees Celsius below zero, and it was very likely that it would not be able to hit again.
A huge challenge for refrigeration systems
Li Yu, manager of the mechanical and electrical project department of the National Bobsleigh Center, said: "The refrigeration machine room is like a heart, only if the heart beats strongly and continuously, and the liquid ammonia is continuously injected into the ice dragon's body, the ice dragon on the track can survive." As the refrigerant of the "Snow Dragon", the refrigeration tube will be filled with gas-liquid mixture of minus 18 degrees Celsius and circulate in the body of the "Dragon" to provide it with a steady stream of low temperature and ensure that the ice does not melt.
Even more difficult than that is, there are a total of 10,811 refrigeration pipes, and the welders need to weld them section by section. And every welding can not have any details such as gap pores, otherwise it must be planed open from scratch, otherwise it is likely to cause the problem of liquid ammonia leakage. Temperature, humidity and even can directly affect the quality of welding. These have extremely high requirements for the methods and care of workers. In order not to affect the quality of welding, the welder master still works in the shed close to 40 degrees Celsius in the hot summer, and strives for excellence.
The welders carry out welding work in the shed
Screenshot of the documentary "Building Dreams of the Winter Olympics"
"Ice making - leveling ice - clearing ice" three tedious steps
Bobsleigh is the fastest sport at the Winter Olympics. When racing, the average speed is about 100 kilometers per hour, the maximum design speed can reach 135 kilometers per hour, has always been known as "ice F1", and the high-speed driving of the wind is the biggest attraction of the snowmobile. The IOC stipulates that the ice surface thickness error cannot exceed 5 mm. Even if the track is slightly uneven, athletes who are sliding at high speeds can rush out of the track, even endangering their lives. At the 2010 Winter Olympics in Vancouver, a bobsledge athlete from Georgia, Nordar Kumari Tashvili, accidentally fell during a training session and died. Therefore, the smoothness of the track ice surface is extremely important. Every detail of it determines the performance of the competition, and any negligence may endanger the lives of athletes.
Ice makers need to first spray more than hundreds of times on the concrete surface, forming a layer of 3 to 5 cm of ice on its surface. After the basic spray ice making process, it is more important to level the depressions and bumps that appear on the ice surface. The ice makers first adopted the method of "ice replenishment", using excess ice to fill in the depression. Then use a shovel with an ice knife and scrape it on the ice surface to form a smooth ice surface.
But even after such a complex "ice leveling" step, debris such as dust will still appear on the ice surface, as well as ice slag left by athletes after sliding, which will affect the fairness of the game. Icemakers need to use high-pressure spray guns to quickly remove debris from the ice surface during the short time during the mid-term break of the game to ensure a fair game.
Ice makers are scraping the surface of the ice with ice knives
"Black Technology" in "Snow Dragon"
I. "Terrain Climate Protection System"
Since the Snow Dragon is located on the southern slope, the sunshine time, sunshine intensity and surface temperature are higher than on the north slope. Even with a better refrigeration system, it may still lead to the melting of the ice surface. In order to protect the ice surface of the track and minimize energy consumption, the design team of the National School Car Bobsleigh Center has developed a unique "Terrain Climate Protection System". The use of terrain, awnings, windshields, and sun blinds effectively reduce solar radiation. The awning is equipped with a pedestrian walkway, which is convenient for maintenance workers and can be used as a trail for tourists to visit. The windshield effectively solves the problem of strong winds at night in the mountains. The sun blinds will also be fully opened while the game is in progress, but it will not affect the spectators.
National Bobsleigh Center "Terrain Climate Protection System" @ Visual China
Second, concrete disposable spraying technology
The best way to evenly cover concrete on complex refrigeration pipes is to use spray pouring. The spray gunman is required to spray the concrete at high speed with the spray gun to attach to the outside of the refrigeration tube and solidify quickly. However, the spray gun weighs up to 30 kilograms, and when spraying concrete, it will also produce a huge recoil, which is a great drain on the physical strength of the sprayer. Such a difficult job, China has no previous experience. Chief engineer Li Xiantao also thought of using foreign gunners to participate, but it was a failure for the entire research and development.
Eventually, they approached a blaster who had previously been spraying blast furnace refractories in the steel plant. After a nationwide selection process, the Shooter candidates gathered in Beijing to receive devil training. Under the rigorous training of more than 200 on-site spraying, the first batch of concrete sprayers in China were born. After more than 400 days of construction, the concrete infrastructure of the bobsleigh track has finally come to an end.
Concrete sprayers use spray pouring to evenly cover the concrete on the refrigeration pipe
One after another, these difficult and huge difficulties and tests all consume huge manpower, material resources and financial resources. But none of them "brought us down". On December 29, 2020, after more than two years, the construction of China's first and only bobsleigh track that meets the standards of the Winter Olympics was completed. On February 9, 2022, Ivo Feriani, Executive Committee member of the International Olympic Committee and president of the International Snowmobile Federation, issued the track certification certificate of the National Bobsleigh Center And the steel frame bobsleigh to The Beijing Enterprises Group.
"My dear Chinese friends, the Yanqing National Bobsleigh Center is the best venue in the world, and you have no doubt, no doubt, you can be convinced of this. With my knowledge of venues around the world, I know that the National Bobsleigh Center is the best. The owners have built an excellent venue. In the history of bobsleigh and steel frame snowmobile venues, I think this venue is unparalleled! Ivo Feriani praised.
(Written by Huang Yan Yuanzhi)
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