软土地基上深水高墩桥梁的地震破坏机理研究

With large-scale construction of cross-sea/cross-river high-pier bridges in deep water built on soft soil foundation in China, it still lacks in-depth and systematic researches of these bridges under earthquakes because of the effects of dynamic interaction between multiple mediums and structure (multiple mediums including soil and water). This research will focus on the high-pier bridge in deep water built on soft soil foundation. Combining the theoretical analysis, numerical simulation and centrifuge shaking table test, this project will research the mechanism of dynamic interaction between multiple mediums and pier, establish the analytical model and method of the dynamic interaction between multiple mediums and pier, and summarize the seismic effects of multiple mediums on the response to the pier. Then, the damage mechanism of the bridge under earthquakes considering the multiple mediums will be studied, and the key factors which have a strong impact on the structural damage and the correlation between the factors will be revealed. The research results can provide a theoretical basis and technological supports for improving the seismic design of the cross-sea/cross-river high-pier bridges.

我国跨海跨江深水高墩桥梁大规模建设，其建设场地多为沿海和江河流域软土地基，地震作用下多介质（土和水介质）对结构动力作用效应的存在使得对此类桥梁结构的认识还不够深入。本项目拟以软土地基上深水高墩桥梁为研究对象，以理论分析、数值仿真和离心机振动台模型试验相结合，研究地震作用下多介质与桥墩的动力相互作用机理，建立多介质-桥墩动力相互作用模型和分析方法，归纳总结多介质作用对桥墩地震反应的影响规律；研究考虑多介质影响下高墩桥梁地震损伤破坏机理，揭示影响其地震损伤的致灾因素及各影响因素之间的关联性。项目研究成果可为我国跨海跨江高墩桥梁结构的抗震设计提供理论基础和技术支撑。

跨海跨江桥梁结构的抗震问题是当前国内外重点关注的研究课题。利用离心机振动台，设计实施了考虑水-结构相互作用和土-结构相互作用的桥墩地震响应振动台试验，分析了考虑多介质体作用的桥墩地震响应特征；利用LS-DYNA有限元软件建立了考虑多介质体作用的桥墩地震响应精细化模拟方法，参数分析了多介质作用对桥墩地震响应的影响规律；结合结构损伤分析模型，建立了多介质体作用下桥梁结构地震损伤分析方法，开展了考虑多介质体作用的桥梁地震损伤分析，揭示了跨海跨江桥梁结构的地震致灾作用机制，并利用MR阻尼器研究提出了桥梁损伤均匀化控制方法。项目研究成果可为深水桥梁结构的抗震理论与设计提供支撑。