Study on the Selection of High-Energy Protective Steel Box Shed Against Post Earthquake Collapse
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摘要: 我国西部地区地形地质条件极其复杂,山高坡陡,地震频发,从2008年汶川地震、2013年四川芦山地震、2017年九寨沟地震等历次山区强烈地震后的公路震害显示,对公路破坏最大、抢通保通难度最大、破坏影响最深远的是高位崩塌等次生地质灾害。为解决震后高位崩塌等次生灾害对山区公路的破坏,满足生命线公路的保通需求,以“应急响应快、安装风险小、地基要求低、适应能力强、抗冲击能力强”为切入点,提出了“避、缓、抗”、“避、缓、延”、“避、延、耗”三种理念的装配式钢箱棚洞。
基于ANSYS/LS-DYNA的显示算法,对钢箱棚洞在落石冲击荷载下进行全过程模拟,依据落石最大冲击力,棚洞各部件吸能能力和钢箱结构等效应力等动力响应指标对三种类型钢箱棚洞抗落石冲击性能进行了深入分析,掌握了钢箱棚洞受力机理;利用钢箱结构屈服应力、基底承载能力和结构是否侵限为标准对三种防护理念的钢箱棚洞极限承载能力进行了研究。
结果表明:三种钢箱棚洞的结构形式合理,防护能级均能达到1 000 kJ,相对于传统钢棚洞或钢筋混凝土棚洞,其防护能级提升较大;安装的改性橡胶支座为可压缩超弹性材料,自恢复性良好能够重复多次使用,可通过其环向大变形进行储能,延长冲击时间以减小落石冲击力,提高棚洞抗冲击能力;柔性网防护系统通过防护网的大变形缓释并辅以其他系统耗能组件耗散能量,对比分析后其防护效果最佳,结构经济性和抗震性最佳,极限抗冲击能级可达2 000 kJ。研究结果为钢箱棚洞缓冲装置材料、构造的选型设计、优化和后续1∶1原型试验提供了依据。Abstract: 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.-
Key words:
- earthquake /
- shed /
- soil cushion /
- modified rubber bearing /
- flexible protective structure /
- high level collapse
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