An improvised steel stand designed based on the characteristics of landform, terrain and foundation soil of outdoor venues of the Winter Olympics. Photography: Liu Zhao, reporter of http://m.cqnews.net
http://m.cqnews.net-19:00 December 30 (Reporter: Qin Sisi) The 2022 Beijing Winter Olympics is drawing near. By now, everything is ready. There are a number of “black technologies” “made in Chongqing” that are supporting this world-level sports event.
The earth below the venue is all frozen earth. Then will the structure collapse? Is there any chance that the athletes get hurt in such a cold environment and perform below par? How do we guarantee safety of the facilities?
It is reported that Chongqing University took the lead in many special key projects and tasks of “scientific and technological Winter Olympics”, among which there were “key technologies of foundation treatment and safe operation and maintenance of large-area and high-capacity temporary facilities in severe cold mountainous areas” and “environmental element impact assessment and on-site decision support system for snow sports event venues”.
It is reported that the projects undertaken by Chongqing University are empowering Beijing Winter Olympics from different dimensions utilizing scientific and technological approaches. It does not only guarantee safety of temporary facilities of Winter Olympics, but also provides scientific analysis and decision-making basis for the snow sports athletes and coaches of China.
Application of key technology for rapid treatment of frozen soil foundation of anti-freezing and thawing circulating frozen soil for temporary facilities in severe cold mountain area. Photography: Liu Zhao, reporter of http://m.cqnews.net
>> Underground “bolts”, guaranteeing “basic safety” of frozen soil in emergencies
At Winter Olympics venues, a great number of temporary facilities are built on mountainous terrain with complex slopes. Foundation deformation is one of the frequent problems of the frozen soil layer.
According to Professor Yang Zhongping from the School of Civil Engineering of Chongqing University, a member of the “Scientific and Technological Winter Olympics” Team, when the temperature drops below zero, the moisture in soil turns into ice. With change of the climatic conditions, the frozen soil would experience constant frost heave and thawing settlement. If the foundation soil changes unexpectedly, the established foundation will be impacted and the structures aboveground will be unstable.
In view of the fact that the bearing capacity of frozen soil in severe cold conditions is significantly influenced by the temperature and loading effect, Professor Yang Zhongping and its team developed the patented new pile for rapid treatment of freeze-thaw resistant circulating frozen soil foundation suitable for large-area complex structural load in severe cold mountainous area, taking into consideration the characteristics of the foundation soil and the upper loading effect of the venue.
The reporter noticed at the site that the new piles looked like enlarged bolts. Yang Zhongping told the reporter that the spiral blade design was adopted for the body of the new pile to facilitate mechanical screw drilling construction, and realize high-speed and weak-disturbance construction. The construction of a single pile takes only some 10 minutes. The piles can be recovered by rotating in a reverse direction, which coincides with the idea of green Olympics. Besides, the new pile has a significantly increased bearing capacity. The part of the pile body in the frozen soil layer has a spacing sleeve that separates the central bearing steel pipe with the surrounding frozen soil, thus eliminating the impact of frost heave and thawing settlement of the foundation frozen soil.
“The new piles are not used extensively and are only used as an emergency measure for the Winter Olympics, as guarantee of the ‘basic safety’.” Said Yang Zhongping.
Workers of “Scientific and Technological Winter Olympics” are showing the new science and technologies. Photography: Liu Zhao, reporter of http://m.cqnews.net
>>Temporary facilities should be firm and comprehensive “inspection” is carried out during and after construction.
It is reported that except for a few permanent venues such as the speed staking stadium and Ice Cube, most of the supporting infrastructure of sports events such as spectators stand, living quarters and healthcare facilities are mainly temporary facilities, including spectator stands, broadcasting towers, bridges, LED screens, toilets and temporary rooms, whether in the process of construction or use. Specifically, the spectators stands are large in area and crowded, and the firmness and safety of the frame are critical. In order to ensure firmness and safety, the "Scientific and Technological Winter Olympics" Team of Chongqing University developed a safety operation and maintenance monitoring system for large-area high-capacity temporary facility and a UAV physical examination system for scaffolds in the complicated terrain of severe cold mountainous areas to carry out "constant check-up" for these temporary facilities.
At the laboratory testing site, the reporter noticed that at each “joint” of the scaffold, a number of bolts were used to connect and fix the “bones”. In Yanqing alone, there are 100,000 bolts like this. But is the scaffold really firm? How can we test the scaffold?
The reporter found that each bolt was painted with unique reflecting material in advance. If a bolt is not installed properly, the display screen would give a feedback immediately. This saves time and manpower, and guarantees safety and firmness of the temporary facilities to the greatest extent. According to Hui Yi, a researcher from the School of Civil Engineering, and a member of the "Scientific and Technological Winter Olympics" Team, Chongqing University developed two testing systems, the lift-type testing system and UAV testing system to meet the different requirements. They can be used to test whether the node bolts are properly installed in an effective and accurate manner. The Team has visited the venues in Yanqing and Chongli a number of times, and carried out thorough scanning of each node. The result showed that the structures all met the using requirements.
Environmental element impact assessment and on-site decision support system for snow sports event venues. Photography: Liu Zhao, reporter of http://m.cqnews.net
“A picture alone is enough for check-up of bolt connections within the coverage of the picture.” Said Hui Yi.
The firmness of each “joint” is guaranteed this way during the construction. Besides, in order to ensure the safety of large-scale temporary facilities under severe cold, mountain and strong wind conditions, Professor Liu Gang, member of the "Scientific and Technological Winter Olympics" team of Chongqing University and professor of the School of Civil Engineering, developed a safety operation and maintenance monitoring system for large-area and high-capacity temporary facilities in complicated terrain in severe cold mountain areas. "By installing environmental sensors such as temperature and humidity and structural response sensors for vibration, inclination and strain on temporary facilities, the status of temporary stands can be monitored in real time and 'check-ups' be carried out from time to time." According to Professor Liu Gang, the team has installed a total of 30 sets of equipment in the venues of Chongli and Yanqing to monitor the safety of temporary facilities. The equipment will not be removed until after the Winter Olympics and the Winter Paralympic Games. During this period, all monitoring data will be transmitted to the on-site operation and maintenance personnel in real time to allow them to maintain the temporary facilities in time.
The unmanned aerial vehicle gives warning when it discovers any unfastened steel frame buckle. Photography: Liu Zhao, reporter of http://m.cqnews.net
>>3D wind tunnel modeling provides individualized training scheme for athletes
Besides the “black technologies”, the special project in which Chongqing University participates as part of the “Scientific and Technological Winter Olympics” focuses on the research of wind environment of the snow sports field, and provides decision-making basis and support for athletes and instructors of China.
The factors that affect the skiing performance of athletes include body shape, skills and tactics of the athlete, track conditions, snow conditions, wind speed and the characteristics of ski equipment. Athletes are also affected by gravity, air lift and resistance, supporting force of the ground and friction, and skeletal muscle force during taxiing. Among them, air resistance is closely related to the posture of the athletes. Based on the monitoring data, the wind speed at the field can be as high as more than 20-30m/s. In such a case, the direction of the wind speed in the field environment will also pose a great impact on the skiing performance of athletes.
Through field survey and 3D modeling, Yan Bowen, an associate professor of the School of Civil Engineering and a member of the "Scientific and Technological Winter Olympics" team of Chongqing University, built a practical, efficient and accurate speed drop model for alpine skiers. This model can be used to work out individualized training scheme based on the tactics, skills, equipment and physical fitness of the athlete, and improve their performance during the competition.
“We applied the scientific and technological achievements to the actual projects.” According to Liu Gang, they will try to apply the scientific and technological achievements in more fields and in a more extensive way, to empower the future and development with science and technology.
Source: http://m.cqnews.net
