Numerical analysis of dynamic response and impact resistance of a large-span rock shed in a tunnel under rockfall impact
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摘要: 为研究大跨度棚洞在落石冲击下的力学性能以及轻质土的抗冲击性能，根据所确定的落石冲击能量，利用动力有限元数值方法对山岭隧道大跨度棚洞受落石冲击作用的动力响应进行了分析，研究了棚洞钢筋混凝土结构受落石冲击作用的损伤特性，将不同工况下的冲击深度时程曲线和冲击力时程曲线进行了对比，比较了棚洞顶部回填普通土和轻质土时对落石冲击作用的缓冲效果，并给出了棚洞顶部回填材料及其回填土厚度的建议。Abstract: In this work, based on the determination of the rockfall impact energy and using the dynamic finite element numerical method, we analyzed dynamic responses of large-span shed-tunnels of mountain tunnels under rockfall impact, and investigated the characteristics of damages suffered by the shed-tunnel structure's reinforced-concrete. The impact depth time-history curve and impact force time-history curve under different conditions were presented for comparison and different buffering effects were also summarized for comparison between the common soil and the light soil on which shed-tunnels were constructed. Meanwhile, suggestions concerning the choice of backfilled soil and the propriety of its thickness were proposed. The results from our study will be valuable for the design of mountain tunnels' large-span shed-tunnels and the prevention of rockfall that may damage them.
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Key words:
- solid mechanics /
- dynamic response /
- rockfall /
- impact load /
- large-span shed-tunnel /
- light soil /
- concrete damage
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表 1 材料参数
Table 1. Parameters of materials
材料 ρ/(kg·m-3) E/MPa ν 混凝土 2 500 - - 钢筋 7 800 2.06×105 0.12 土垫层 1 500 15 0.35 落石 2 500 5.0×104 0.3 
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表 2 不同冲击能量下混凝土损伤体积
Table 2. Damage volume of concrete vs. different impact energies
Ei/kJ V/m3 ηV/% 框架 盖板 框架 盖板 65 1.15 0 0.76 0 130 1.73 0 1.14 0 260 2.14 0.58 1.42 2.26 520 3.90 1.02 2.58 4.02 1 040 7.74 1.79 5.12 7.04
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表 3 不同垫层混凝土损伤体积对比
Table 3. Comparison of concrete damage with different cushionss
垫层 V/m3 ηV/% 框架 盖板 框架 盖板 土垫层 2.144 0.576 1.42 2.26 轻质土 2.032 0 1.34 0
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表 4 钢筋应力对比
Table 4. Comparison of steel stress
垫层 σi/MPa α/m ηα/% 框架 盖板 框架 盖板 框架 盖板 土垫层 95.3 78.9 172.8 120.8 7.35 5.53 轻质土 95.0 22.9 133.6 11.2 5.68 0.51
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表 5 位移对比
Table 5. Comparison of displacement
垫层 s0/mm si/mm ss/mm 框架 盖板 框架 盖板 框架 盖板 土垫层 2.7 3.9 2.0 2.4 0.4 0.6 轻质土 2.2 3.4 2.0 2.4 0.2 0.2
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表 6 不同垫层厚度下混凝土损伤体积
Table 6. Damage volume of concerte at different thicknesses
l/m V/m3 ηV/% 框架 盖板 框架 盖板 0.6 1.79 0.43 1.18 1.70 1.0 1.84 0 1.22 0 1.4 2.03 0 1.34 0 1.8 2.06 0 1.36 0 2.2 2.25 0 1.49 0
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