Study on the Selection of High-Energy Protective Steel Box Shed Against Post Earthquake Collapse

The terrain and geological conditions in Western China are extremely complex, with high mountains and steep slopes and frequent earthquakes. From the Wenchuan earthquake in 2008, Lushan earthquake in 2013, Jiuzhaigou earthquake in 2017 and other strong earthquakes in mountainous areas, the secondary geological disasters such as high-level collapse are the most destructive, difficult and far-reaching ones. In order to solve the damage of secondary disasters such as high-level collapse after the earthquake to mountain roads and meet the needs of lifeline roads, taking "quick emergency response, small installation risk, low foundation requirements, strong adaptability and strong impact resistance" as the breakthrough point, the paper put forward three concepts of "avoid, slow, resist", "avoid, slow, delay", "avoid, delay, consume" of steel box shed tunnel.
Based on the display algorithm of ANSYS/LS-DYNA, the whole process of steel box shed under rockfall impact load was simulated. According to the dynamic response indexes such as the maximum impact force of rockfall, the energy absorption capacity of each part of shed and the equivalent stress of steel box structure, the rockfall impact resistance performance of three types of steel box shed was analyzed, and the stress mechanism of steel box shed was mastered. The ultimate bearing capacity of steel box shed with three kinds of protection concept was studied.
The results showed that:the structure of three types of steel box shed was reasonable, and the protection energy level could reach 1 000 kJ, which was higher than that of traditional steel shed or reinforced concrete shed; the modified rubber bearing was a compressible hyperelastic material with good self recovery, which could be reused for many times. It could store energy through its large circumferential deformation, prolonged the impact time and reduced the drop. The protection effect of the flexible net protection system was the best, the structure economy and seismic performance were the best, and the ultimate impact energy level could reach 2 000 kJ. The research results provided the basis for the design and optimization of the material and structure of the buffer device of the steel box shed tunnel and the subsequent 1:1 prototype experiment.