Abstract: In order to study the dynamic response and damage of double-column bridge in mountainous area impacted by rockfall, a double-column bridge in western mountainous area was taken as the research object. LS-DYNA was used to establish a high-precision three-dimensional solid collision finite element model. The influence of rockfall parameters on the bridge dynamic response and damage was analyzed, and the time-history curve of impact force of pier was discussed and compared with the calculation formula of equivalent impact force given by various national norms. The research results show that the damage caused by rockfall impacting the middle of bridge pier is larger than that of other locations; the influence of rockfall velocity on the peak value of impact force is more significant, and the influence of rockfall mass on the duration of impact force and the maximum horizontal displacement is more significant when the pier is impacted. Besides, the damage degree of bridge pier increases with the increase of kinetic energy of falling stone, while the damage degree of rockfall mass to the damage degree of bridge pier is more significant; moreover, with the increase of rockfall mass, the damage form of pier tends to be more inclined to shear damage of oblique section. The calculation results of the impact force calculation formula of “Specifications for Design of Highway Subgrades” and “Technical Manual of Railway Engineering Design” in China are relative small, and the design is not very safe. The calculation results of the Japan Highway Public Corporation formula are in good agreement with the peak values of impact force of numerical simulation, which is recommended for engineering design.

Key words: bridge engineering; rockfall impact; numerical simulation; dynamic response; damage

摘要： 为研究落石撞击山区双柱式桥梁的动态响应与损伤，以西部山区一座双柱式桥梁为研究对象，采用LS-DYNA建立了高精度三维实体碰撞有限元模型，分析了落石参数对桥梁动态响应及损伤的影响，并将桥墩撞击力时程曲线与各个国家规范给出等效撞击力计算公式进行对比和讨论。研究结果表明：落石撞击桥墩中部造成的损伤相比其他位置大；落石速度对于撞击力峰值的影响更为显著，而落石质量大小对桥墩被撞击时的撞击力持续时间及最大水平位移影响更加显著；桥墩损伤程度是随着落石动能增加而增加，而落石质量大小对桥墩损伤程度更为显著，且落石质量增加使桥墩的损伤形式更偏向于斜截面受剪；我国《公路路基设计规范》和《铁路工程设计技术手册》撞击力计算公式计算结果偏小，设计不太安全，日本道路公团公式的计算结果与数值模拟的撞击力峰值吻合良好，建议工程设计采用。

关键词: 桥梁工程；落石撞击；数值模拟；动力响应；损伤