In urban planning and development, the state has proposed that urban development should introduce urban aesthetics into the architectural field and promote the harmonious coexistence of man and nature. U-shaped beams are the most novel viaduct bridge type used in urban rail transit. They have the characteristics of good noise reduction effect, low building height, high space utilization, and beautiful appearance. They are currently recognized as being able to replace traditional box girders. However, ordinary U-shaped beams have always been restricted by factors such as small span, complex stress, cumbersome production, and difficulty in construction.
This project has established a systematic and complete integrated technical system for "double U-box" beams from aspects such as architectural design, beam research and development, construction control, equipment manufacturing, process standards, and post-evaluation, improving the engineering environment adaptability of U-beams.
1) For the first time in the world, the construction concept of composite variable cross-section "double U box" beams was proposed and the systematic design was completed. Creatively integrating the box structure into the overall design of the U-shaped beam not only greatly improving the structure and mechanical properties of the U-shaped beam, but also through the precise design of the second parabola of the beam shape, it achieves the integration of adjacent ordinary U-shaped beams. The overall integration of the line has achieved the perfect unity of mechanics and aesthetics of the building structure. The "double U-box" beam has achieved a major breakthrough with a maximum span from 50m to 70m, greatly improving the U-shaped beam's engineering environment adaptability.
2) Developed high-precision segment assembly design and integrated construction technology for "double U-box" continuous beams, and successfully realized the segment assembly of U-shaped beams. Creatively apply the concept of "finite step predictive control" in the advanced control field to the design and construction line control of prefabricated segment beams. It realizes high-precision line shape control of the beam body during prefabrication, and effectively solves the influence of calculation errors and assembly errors during segment assembly construction. The maximum linear deviation of all completed bridges is 3.8mm, and the vertical deviation is 6.1mm. The construction error is reduced from centimeter level to millimeter level. The implementation of segmented assembly shortens the project cycle by more than 50%, saves transportation costs by more than 55%, and greatly reduces the impact of construction on traffic and the environment.
3) For the first time, a large lifting ladder-type leapfrog suspension crane with high-precision 360-degree full-rotation adjustable eccentric balance was developed for rail transit construction. The machine has a super lifting capacity of 120 tons. It adopts non-flexible four-point lifting and thrust self-aligning bearings to achieve 360-degree rotation of the hook. It also has millimeter-level three-dimensional attitude adjustment capabilities with translation in three directions and rotation in two axes. Through modular and lightweight design, the machine is convenient to be placed in place, flexible to disassemble and disassemble, reducing transfer costs by 70%, dead weight by 30%, and cost by 60%.
4) Develop a mold scheduling and control system with "multi-objective optimization algorithm" as the core, which improves the efficiency of manufacturing large-scale complex beams. The intelligent mold scheduling and control system adopting the "global goal optimization algorithm" achieves efficient recycling of the bottom mold, reduces the template production cost by about 20%, reduces the labor use of template operation by more than 30%, and the average daily output of segmented beams is 5 pieces., the average template turnover speed reaches 2.5 days per turnover.
This project has applied for a total of 12 national patents, including 2 authorized invention patents and 10 authorized utility model patents; and published 16 papers. After appraisal and technical novelty search, the overall level has reached the domestic leading and international advanced level.
The research results of this project have all been applied to the construction of rail transit in Shanghai, Guangzhou, Shenzhen and other cities, saving a total of approximately 85 million yuan in construction costs and creating direct economic benefits of 4.7 billion yuan. According to statistics, 60% of the beams in new domestic rail transit adopt U-shaped beam design. The results of this project will have broad market application prospects and reflect huge social and economic benefits.