Photo: Aerial photo of the National Bobsleigh Center Courtesy of the interviewee (the same below)
Xinmin Evening News (correspondent Cai Shangru Zhao Anguang reporter Qiu Yingqiong) At an altitude of 2198 meters above sea level, the Beijing Winter Olympic Venue - National Bobsleigh Center, built by Shanghai Baoye, a subsidiary of China Metallurgical Corporation, is not only the first bobsleigh track in China, but also one of the newly built competition venues with the highest design difficulty, the greatest construction difficulty and the most complex construction process in this Winter Olympic Games.
The National Bobsleigh Center is the only bobsleigh track in China, the seventeenth in the world and the third in Asia to meet the Olympic competition standards. During the Beijing 2022 Winter Olympics, it will undertake all the competition contents of the three sports of bobsleigh, steel frame bobsleigh and bobsleigh. Because it resembles a giant dragon hovering at the top of a mountain range, the Beijing Winter Olympic Organizing Committee also gave it a nice name - "Snow Dragon".
According to the person in charge of the Shanghai Baoye project, because the project is highly professional, the site requirements are stringent, and the popularity and development level of the mainland in ice and snow sports is still a certain gap with European and American countries, the experience in the construction of the corresponding Winter Olympic venues is basically zero, and the core construction technology, materials and experience are monopolized by European and American countries, which means that everything in the construction of the project must start from scratch.
The ice temperature has undergone more than a thousand repeated commissioning
The National Bobsleigh Centre has a unique 360-degree swivel and the track can glide at a maximum speed of 134.4 km/h. Special construction needs have opened up a number of domestic "firsts". The flattening error of the surface of the special-shaped twisted track structure should be controlled within 1 mm, and the developers boldly innovated and used shotcrete for the main structure for the first time. In order to build this 1975-meter-long concrete track with three-dimensional twisting and being able to withstand more than 400 freeze-thaw cycles, the project team has worked hard to independently develop a new concrete material, independently trained the first concrete sprayer in China, and ensured the success of the one-time pouring of the track with millimeter-level precision.
The design of the bobsleigh track is complex, and the curvature of the space varies greatly, so the accuracy of ice making and repair of the track is extremely high. Before the official ice making of the track began, the project department combined the feedback from all parties and the actual situation on the spot, and adjusted the ice making temperature in time through ammonia throttling to adapt to the ambient temperature. After more than a thousand attempts, the project team finally found a "match" between the ice temperature and the outside temperature, and produced the ice with the best speed and durability, and it was not appropriate to make dents on the ice surface.
Track ice making requires the ice maker to use a professional sprinkler to spray the heated pure water mist evenly on the surface of the low-temperature concrete layer by layer, so that the water mist condenses and solidifies into ice. When encountering the bend of the high wall, spray along the high wall from above, so that the natural water below is ice.
The formation of the ice track must maintain a continuous water spray operation, otherwise it will cause the humid air to freeze on the ice surface to form a frost layer, and the frost layer will capture the air bubbles in the ice, when these bubbles move outward, it will form small dents, and a small dent may affect the athlete's sliding trajectory, and even endanger life safety. In the end, the ice-making team continuously sprayed hundreds of layers of extremely thin water mist, making the ice channel with a total area of 7,000 square meters and a thickness of 50 mm "natural".
Pictured: Construction workers check the ice surface
Ice surface repair needs to be guaranteed to be formed
For the in and out of the bending trajectory, and the poor ice-making effect caused by the ice falling off, the ice repairman's craftsmanship is tested. After the ice repairer mixes the best quality ice repair material natural snow and water, it is filtered and used special ice repair tools to repair the ice.
Ice surface finishing is the last step, and its precision directly affects the smoothness and sensory quality of the ice channel. The ice repairer first touches the ice surface with his hand to feel its flatness. For uneven places, the sand ice prepared in advance is spread out in the uneven parts, and the ice track with the changing curvature of the space is trimmed using the custom ice repair tool developed in-house. At this time, it is necessary to master the angle of the scraper and maintain the strength to ensure the stability of the blade blade, and the ice forming surface must ensure that the sliding trajectory is formed together. After the ice surface is formed, the ice surface is sprinkled with water for maintenance.
It is reported that since the construction of the National Bobsleigh Center Project in 2018, the Shanghai Baoye project team has exerted the comprehensive strength of the whole industry chain, and after a large number of scientific and technological research and development, it has accurately overcome a number of track technical problems, formed a complete set of its own construction technology, successfully developed and completed the high-strength, high-performance track special spraying concrete, achieved the goal of completing the spraying task by the Chinese people themselves, and filled the domestic gap; the ammonia refrigeration system and the track ice repair technology are adopted. Set up the first bobsleigh track ice maker team in China to start the first in China.
The project participated in the key special project of the 2018 National Key R&D Plan "Science and Technology Winter Olympics", formed 5 track technical standards and acceptance standards, fully met the international certification requirements of the track, and achieved a breakthrough of zero in China. The National Bobsleigh Center project is also a science and technology research and development project, and has applied for 131 patents (including 57 invention patents) so far, and has won a number of national, provincial and ministerial awards.