Located in Pingtang County, Qiannan Prefecture, Guizhou Province, the 500-meter spherical radio telescope (FAST project for short, known as the "China Sky Eye") is currently the World's Largest Single Radio Dish Telescope. Construction began in 2011 and is scheduled to be completed in 2016. Become a world-class radio astronomy research center.
The cable net manufacturing and installation project is one of the main technical difficulties of the "China Sky Eye" project. It is not only the cable-net structure with the largest span and the highest precision in the world, but also the first cable-net system in the world that adopts a displacement work method. The key indicators are far higher than the regulatory requirements in related fields at home and abroad, and there is no experience or data to learn from in the world. At the same time, the total weight of the cable net is about 1,300 tons. Due to site conditions, all cable structures must be assembled at high altitude.
The National Astronomical Observatory, the construction unit of the "China Sky Eye" project, opened a national bidding process. Finally, GXOV Precision Machinery Technology Group accepted the challenge and successfully developed the world's first ultra-high fatigue strength steel cable net.
The steel cable net of "China Sky Eye" is very heavy and is pulled very frequently, so it needs ultra-high fatigue strength. Large-scale projects in China include the steel cables on cable-stayed bridges. The strength of the cables is 200 MPa and 2 million bends. However, the "China Sky Eye" has higher requirements for the cable network and is extremely difficult to construct. There are many well-known domestic research institutes in China. After several tests, the institute and factory failed to meet the design requirements of the National Observatory.
GXOV focuses on the research and production of anchoring structures. The GXOV R&D team concentrates on researching the anchoring mechanism, and adopts theoretical analysis, finite element calculation and test methods to calculate and optimize the anchors, and improves and perfects the Chinese prestressed anchor system. The problem of unstable anchoring efficiency coefficient of domestic anchors lays the foundation for the application of domestic anchors in nuclear power plants and ultra-low temperature storage tank projects; the fatigue resistance design of the cable anchoring unit is studied, so that the fatigue performance of the steel stranded cable system meets international standards.
In 2011, GXOV completed the "GJ Steel Strand Bundle Extrusion Cable System" and won the second prize of provincial scientific and technological progress;
In 2014, GXOV completed "Innovation and Application of Key Technologies for Modern Prestressed Concrete Structures" and won the first prize of National Science and Technology Progress Award.
The "China Sky Eye" cable net is the world's largest cable net structure with the highest precision. It is also the world's first cable net system that adopts a displacement working method. Its reflective surface area is about 30 football fields, and the technical difficulty is not mentioned. And Yu, the technical problems that need to be overcome run through the entire process of cable net design, manufacture and installation. The key technical problems mainly include: super-large span cable net installation plan design, ultra-high fatigue performance steel cable structure development, and ultra-high precision cable structure manufacturing Craft and so on. For example, the control accuracy of the main cable segment must be within 1 mm, and the position accuracy of the main cable node must be 5 mm. The entire cable net has a total of 6670 main cables, 2225 main cable nodes and the same number of pull cables. Taking the development of high-stress steel cables as an example, the fatigue performance requirements of the "China Sky Eye" project are equivalent to twice the specified value of the code, and there is no experience or information that can be used for reference at home and abroad.
The development of cable nets has gone through the process of "failure-recognition-modification-perfection", which lasted for one and a half years. In the end, GXOV completed the technical research and realized the system solution to the cable fatigue problem, the main cable network accuracy control technology and method, Three independent innovations such as rigid and flexible adaptive coordination issues, invented cold-cast extrusion composite anchoring technology, high-strength pre-stressed steel wire and steel strand combined cable manufacturing technology, and developed new cable materials that meet the requirements. The packaging materials and manufacturing process highlight four characteristics: the world’s largest span and the highest precision; engineering cables can withstand stress twice as high as domestic and foreign standards; the first reflective surface adaptive connection mechanism; the first to create cable products in the industry Information management system.
The successful research and development of the cable net project has enabled the "China Sky Eye" project to avoid the use of Japanese carbon fiber cables with a construction cost of more than 600 million yuan, saving the country at least 480 million yuan in costs. GXOV has obtained the "China Sky Eye" project cable net manufacturing and installation The contract became a unit that participated in the “China Sky Eye”, a major national scientific project, and was finally highly affirmed by the National Astronomical Observatory of the Chinese Academy of Sciences (owner) and Beijing Institute of Construction Engineering Co., Ltd. (on-site supervision).
The cable net project successfully solved the key technical problems of FAST construction, and enabled China to have the world's leading observation equipment in the field of radio astronomy research. It has formed 12 independent and innovative patents, including 7 invention patents, and the results have been reviewed by international experts The meeting was recognized by a foreign expert group. In addition to being successfully applied to the "China Sky Eye" project, these results have greatly improved the R&D and manufacturing capabilities of China's cable structure engineering field, and will also be applied to other areas of the national economy. It has been applied to projects such as the No. 2 Bridge of Binshui New Town in Kaiyuan City, the Pili Qinghe Bridge in Xinjiang Ili, and the STARBAZZR Cable-stayed Bridge in India, with significant economic benefits. At the same time, after certain structural simplifications or changes, the cable net technology can be widely used in cable projects such as highways, railways and municipalities.
GXOV participated in the design and construction research of the "500m Aperture Spherical Radio Telescope Ultra-large Space Structure Engineering Innovation and Practice" project, and solved the problem of the "China Sky Eye" 500MPa ultra-high fatigue stress amplitude cable system, and won the 2015 China Steel Structure Association Science and Technology Special Award , The first prize of Beijing Municipal Science and Technology Award in 2016, and the first prize of provincial technological invention in 2016. The GXOV R&D team has a deeper understanding of the engineering practice of prestressed anchors and cables. It has successively obtained 30 related invention patents and actively participated in the formulation of relevant Chinese regulations. The editor-in-chief of JT/T850-2013 "Extrusion Anchor Steel Strand Cable ".