考虑地形效应的斜坡桥桩抗震性能及设计方法研究

山区斜坡的地形效应可对地震作用产生数倍增幅，这将显著威胁斜坡桥桩抗震安全性。依照我国现行规范进行斜坡桥桩抗震设计时存在：缺乏可靠手段计算斜坡地形效应影响；缺乏适用于斜坡地形的桩受力变形计算方法；缺乏罕遇地震下斜坡桥桩抗震设计方法。.本项目拟首先采用波函数展开法揭示斜坡地震波传播规律，提出斜坡桩基础地震动输入方法，形成计算斜坡地形效应的可靠手段；然后结合能量变分原理、有限元模拟与斜坡桥桩拟静力试验，揭示斜坡桩—地基耦合震动规律，提出适于斜坡地形的桩—土动力相互作用模型，形成斜坡桥桩抗震设计中地基抗力计算方法，服务于斜坡桥桩抗震设计的桩受力变形计算；最后基于理论研究、有限元模拟、增量动力分析法结合概率统计提出考虑斜坡地形效应的桥桩抗震性能指标参考值，对罕遇地震下难以满足弹性变形要求的斜坡桥桩提供设计指导。.综上，本项目研究成果对斜坡地形桥桩基础抗震设计与抗震安全性评价具有重要指导意义。

The slope topography effect could multiply the seismic load, which will significantly threaten the seismic safety of slope bridge piles. At present, there are some defects in the seismic design of slope bridge piles in the existing seismic codes: lack of reliable method to calculate the influence of slope topography effect; lack of calculation procedure for evaluating the kinematic response of slope bridge piles; lack of seismic design method for the slope bridge piles under a rare earthquake.. In the beginning, this project intends to reveal the propagation pattern of slope seismic wave based on the wave function expansion method, proposes a seismic motion input method for the slope pile, and form a reliable method to evaluate the effect of slope topography. Then, reveals the mechanism of the coupling vibration between slope pile and surrounding soil based on the variation principle, finite element simulation and pseudo-static test. By considering the coupling vibration between slope pile and surrounding soil, a nonlinear kinematic soil - slope pile interaction model will be proposed. The calculation method of foundation resistance in seismic design of pile foundation is formed based on the kinematic soil - slope pile interaction model, which serves the calculation of pile deformation. Finally, the influence of slope topography on the seismic performance index of slope pile foundation is evaluated based on theoretical research, finite element simulation, IDA method and probability statistics. The proposed performance index of pile foundation will provides design guidance for the slope pile foundation which inevitably generates plastic deformation under rare earthquake. . In summary, the research results have significant instruction for seismic design and seismic safety evaluation of slope bridge pile foundation.