研究改进动水压力算法的近断层区深水桥梁抗震设计

With the rapid development of transportation infrastructure, cross-sea, river and reservoir bridges are emerging, and some of these deep-water bridges are close to or even across active fault regions with high earthquake intensity. Because of the large acceleration and low-frequency characteristic as well as the long-period pulse effect of such kind of near-fault earthquakes, the vibration state and dynamic response feature of these bridges are affected significantly under hydrodynamic environment. However, related research and specifications are inadequate, and therefore the seismic design of such special bridges under the unique dynamic excitation is a scientific problem to be solved. Firstly, based on both the classic fluid-structure interaction theory and radiation wave theory, the action mechanism of pulse characteristic of near-fault ground motions on the hydrodynamic pressure and structural response is to be studied for deep-water bridges under different water environment parameters and structural parameters, by the ways of theoretical analysis, shaking table tests and full numerical dynamic calculation of typical equivalent single-pier as well as full-bridge models. And then, the applicable scope of Morison equation method will be defined, and the key parameters applicable to typical deep-water bridges will be identified. Moreover, the calculation methods of hydrodynamic pressure by related codes will be checked and correspondingly improved. Furthmore, by considering the dynamic interaction effect between large-diameter cylinder and fluid, as well as the compressibility of water, a simplified calculation method of hydrodynamic pressure for high piers of large-span bridges is to be developed with the radiation wave theory. Finally, the destruction mechanism and failure mechanism of deep-water bridges under pulse-type near-fault earthquakes will be revealed. These above achievements can be as reference for the revision of codes, and provide technical support for the seismic safety of cross-sea, river and reservoir bridges.

随着交通基础设施建设的突飞猛进，跨海(江)及库区桥梁不断涌现，部分深水桥梁靠近甚至跨越高烈度断层区。由于近断层地震动的大幅值、低频谱特性和长周期脉冲效应，显著改变动水环境下深水桥梁的振动性态和动力响应，而相关研究及规范规定尚不完善，此类特殊动力荷载下特殊桥梁的抗震设计是亟待解决的科学问题。本项目基于经典的流固耦合理论和辐射波浪理论，通过理论分析、振动台模型试验及深水桥梁单墩、全桥模型的全数值耦合动力计算，提炼不同的水环境、结构参数下地震动脉冲特性对动水压力和桥梁地震响应的影响机理，界定Morison方程法的适用范围并确定适用于典型深水桥梁的关键参数取值，检验并改进规范算法，考虑大直径柱体-流体间动力相互作用和水体可压缩性，发展基于辐射波浪理论的大跨径深水高墩动水压力的简化算法,揭示脉冲型近断层地震下深水桥梁的破坏机理及失效机制。供规范修编参考，为跨海(江)、库区桥梁的地震安全提供技术保障。

随着我国国土开发强度的不断提高和西部大开发的持续推进，跨海、跨江及跨库区深水桥梁不断涌现，对于我国东南沿海和西部高烈度抗震设防区的此类深水桥梁，面临严重的地震破坏威胁。强震下深水桥梁的抗震设计理论与方法亟待研究。.本项目基于经典的流固耦合理论和辐射波浪理论，以深水单墩、群桩基础及斜拉桥、大跨刚构桥等全桥结构为对象开展系统研究，主要完成了以下研究工作：以全数值流固耦合动力计算方法为基本工具，系统对比了近断层和远场一般地震动激励下，深水桥梁墩周动水压力及桥梁结构动力响应的差异及其影响机理；深入分析并提炼了近断层地震动脉冲参数对深水桥墩、高桩基础地震响应的影响规律；讨论并揭示了地震动强度、入水深度等因素对大跨度深水斜拉桥地震行为及结构损伤的影响规律及作用机理；以辐射波浪理论和势流体全数值算法为基础，检验了Morison方程法等动水压力计算的代表性既有方法在深水桥梁抗震计算中的适用性，界定了Morison方程法在地震作用下水中墩桩动力压力计算中的适用范围；基于辐射波浪理论，推导并回归了适用于不同规格深水桥墩的动水压力改进算法，其有效性、准确性得到检验；深入分析并揭示了强震下深水桥墩、群桩基础的非线性力学行为及其失效机制；基于IDA技术和易损性分析方法，讨论并对比了不同水深下大跨度深水刚构桥的概率性地震损伤特性。此外，还补充研究并总结了波浪、海流复杂环境下深水桥墩地震响应的主要影响参数及其作用规律。研究成果可为深水桥梁抗震设计理论与技术的完善提供参考，可供我国相关规范修编借鉴，可为库区、跨海(江)深水桥梁工程的地震安全提供重要的理论保障和技术保障。.依托本项目，发表（含接收）学术论文15篇，其中SCI、EI期刊论文8篇；登记软件著作权2项；培养毕业硕士生10名（其中优秀硕士论文2人），另新增招收博士生2名；参加国际学术会议10人次、国内学术会议3人次；论文荣获2014年度恢先地震工程学优秀学术会议论文奖。