针对落石被动柔性防护网的试验检验仅采用特定冲击条件，未能有效反映实际可能存在的最不利工况，从而导致通过试验检验的产品在实际工程应用中未能有效实现预期防护目标的现状，采用数值计算方法对不同参数条件下落石被动柔性防护网的力学响应开展了深入研究。首先，基于LS-DYNA，反演了某配置有辅助支撑绳的5000kJ落石被动柔性防护网的足尺冲击试验，对比分析了缓冲距离、关键绳索内力及耗能器伸长量，校验了计算模型。在此基础上，分别针对跨数、落石冲击位置、柱端滑移特征对被动柔性防护网支撑绳内力、钢柱内力及缓冲距离等力学响应的影响开展了参数化分析。结果表明：跨数对被动柔性防护网力学响应影响较小；相同冲击条件下，边柱内力是中柱的2倍以上，且受冲击位置影响显著，边跨冲击最为最不利，通过标准试验检验的系统在边跨受到冲击时边柱仍可能屈曲；柱端滑移摩擦系数的增加使得支撑绳内力增长显著，建议支撑绳设计时安全系数不小于2.0。
Abstract
Only specific impact condition is considered in verification tests of flexible rockfall barriers, which may not be the worst-case scenario in practice. Field investigations show that part of the products which pass the verification tests do not effectively achieve the expected protection target. Therefore, an in-depth research on the mechanical response of a flexible rockfall barrier under different impact conditions was carried out by numerical simulations. Firstly, the full-scale impact test of a flexible rockfall barrier with auxiliary supporting ropes was back-analysed. The numerical model was verified by comparing the breaking distance, rope forces and the elongation of energy dissipators. On this basis, parametrical simulations were carried out to investigate the effects of span number, impact location and post ends sliding characteristics on the mechanical response of the flexible rockfall barrier. The results showed that: the mechanical response of the flexible rockfall barrier was less affected by the number of spans; under the same impact condition, the internal force of the side post was more than twice that of the middle steel post, and was significantly affected by the impact location. In term of the side post, the impact position located at the side span is most unfavourable, and it may buckle even when the system passed the standard verification test; the internal force of supporting ropes will grow significantly with the increasing of the friction coefficient of post ends, and a safety factor of 2.0 was recommended for the design of supporting ropes.
关键词
被动柔性防护网 /
数值模拟 /
参数化研究 /
冲击力学响应
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Key words
flexible rockfall barrier ;numerical simulation /
parametric research /
impact mechanical response
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参考文献
[1] Volkwein A, Schellenberg K, Labiouse V, et al. Rockfall characterisation and structural protection – a review[J]. Natural Hazards and Earth System Sciences, 2011, 11(9): 2617-2651.
[2] Lambert S, Nicot F. Rockfall Engineering [M], New York :Wiley, 2013.
[3] 王东坡，刘浩，裴向军，等. 基于离散元-有限差分耦合的滚石冲击棚洞垫层动力响应研究[J]. 振动与冲击，2021，40(19):246-253.
WANG Dongpo, LIU Hao, PEI Xiangjun, et al. Dynamic response of shed tunnel cushion under rolling stone impact based on discrete element-finite difference coupling[J]. Journal of Vibration and Shock, 2021 , 40(19):246:253.
[4] Yu Z X, Qiao Y K, Zhao L, et al. A simple analytical method for evaluation of flexible rockfall barrier part 1: working mechanism and analytical solution[J]. Advanced Steel Construction, 2018, 14(2):115-141.
[5] 汪敏，石少卿，阳友奎.两种不同组合形式的环形网耗能性能的对比分析[J]. 振动与冲击，2012，31(02):55-61.
WANG Min, SHI Shaoqing, YANG Youkui. Comparative analysis for capacity of energy dissipation of a ring net with two different connection forms[J]. Journal of Vibration and Shock, 2012, 31(02):55-61.
[6] 赵世春，余志祥，韦韬，等. 被动柔性防护网受力机理试验研究与数值计算[J]. 土木工程学报，2013，46(05): 122-128.
ZHAO Shichun, YU Zhixiang, WEI Tao, et al. Test study of force mechanism and numerical calculation of safety netting system[J]. China Civil Engineering Journal, 2013, 46 ( 5) : 122-128．
[7] Geobrugg. https://www.geobrugg.com/zh/Danielsberg-116826.html?markierung=10000
[8] 阳友奎，原振华，杨涛等. 柔性防护系统及其工程设计与应用[M]. 北京：科学出版社，2015.
[9] 中华人民共和国铁道行业标准. 铁路边坡柔性被动防护产品落石冲击试验方法与评价：TB/T 3449—2016[S]. 北京：中国铁道出版社，2017.
[10] EOTA. Guideline for European technicalapproval of falling rock protection kits: ETAG 27[S]. European Organization for Technical Approvals, 2012.
[11] Yu Z X, Zhao L, Liu Y P, et al. Studies on flexible rockfall barriers for failure modes, mechanisms and design strategies: a case study of Western China[J]. Landslides, 2019, 16(2): 347-362.
[12] Yu Z X, Luo L R, Liu C, et al. Dynamic response of flexible rockfall barriers with different block shapes[J]. Landslides, 2021, 18(7): 2621-2637.
[13] Volkwein A, Roth A, Gerber W, et al. Flexible Rockfall Barriers Subjected to Extreme Loads[J]. Structural engineering international : journal of the International Association for Bridge and Structural Engineering (IABSE), 2009, 19(3): 327-332.
[14] Zhao L, Yu Z X, Liu Y P, et al. Numerical simulation of responses of flexible rockfall barriers under impact loading at different positions[J]. Journal of Constructional Steel Research，2020，167: 105953.
[15] Qi X, Pei X J, Han R, et al. Analysis of the Effects of a Rotating Rock on Rockfall Protection Barriers[J]. Geotechnical and Geological Engineering, 2018, 36(5): 3255-3267.
[16] Koo R C H, Kwan J S H, Lam C, et al. Dynamic response of flexible rockfall barriers under different loading geometries[J].Landslides, 2017, 14(3): 905-916.
[17] Moon T, Oh J, Mun B. Practical design of rockfall catchfence at urban area from a numerical analysis approach[J]. Engineering Geology, 2014, 172: 41-56.
[18] EOTA. Evaluation Report for the assessment of ETA – 11/0305 [R]. European Organization for Technical Approvals, 2011.
[19] Livermore software technology corporation (LSTC). LS-DYNA keyword user’s manual volume [R]. LSTC, 2007.
[20] 赵雅娜，余志祥，赵世春.多跨布置式环网柔性被动网结构数值计算方法[J].振动与冲击，2019，38(17):211-219.
ZHAO Yana, YU Zhixiang, ZHAO Shichun．Numerical computing method for a flexible passive network structure with multi-span distributed ring-net[J]．Journal of Vibration and Shock, 2019, 38( 17) : 211-219．
[21] 余志祥，张丽君，骆丽茹，等. 韧性挑篷防护网系统抗冲击性能研究[J]. 岩石力学与工程学报，2020，39(12): 2505-2516.
YU Zhixiang, ZHANG Lijun, Luo Liru, et al .Study on impact resistance of a resilient steel canopy protection system[J]. Chinese Journal of Rock Mechanics and Engineering, 2020,39(12): 2505-2516.
[22] 齐欣，许浒，余志祥，等. 柔性拦截结构中减压环动态力学性能试验研究[J].工程力学，2018，35(09): 188-196.
QI Xin, XU Hu, YU Zhixiang, et al .Dynamic mechanical property study of break rings in flexible protective system[J]. Engineering Mechanics, 2018, 35(09): 188-196.
[23] 齐欣，余志祥，张丽君，等. 被动柔性防护系统对落石冲击作用的传播效应[J]. 西南交通大学学报，2020，55(05): 1085-1093.
QI Xin, YU Zhixiang, ZHANG Lijun, et al. Propagation effect of passive flexible protection system on rockfall impact[J]. Journal of Southwest Jiaotong University, 2020, 55(05): 1085-1093.
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