【摘要】 劲性复合桩作为新型桩基，其动力学特性研究对于工程实践具有重要的理论指导意义。以土动力学与桩基振动理论为基础，系统探讨植入黏弹性饱和土层中的劲性复合桩结构在承受垂直入射地震纵波作用时，其桩顶及桩身部位的竖向位移响应规律。首先，基于Biot多孔介质理论，建立饱和土在柱坐标系下的波动方程。然后，结合劲性复合桩的竖向振动方程，推导出土体骨架纵向位移的封闭级数解，并根据边界条件得到劲性复合桩竖向位移的解析解。最后，通过计算实例与参数分析，揭示在桩端垂直入射P波作用下劲性复合桩-饱和土相互作用系统的动态行为。结果表明：适度缩减劲性复合桩中混凝土芯桩半径并相应增加桩的长度，有助于提升其竖向抗震能力；在高频阶段，水泥土外桩弹性模量增大不利于提高劲性复合桩的抗震性能。在劲性复合桩的设计中，应将混凝土芯桩半径控制在总半径的40%～60%，桩长建议设定为半径的20～40倍，同时水泥土外桩弹性模量应设置为混凝土芯桩弹性模量的2%～5%。更多还原

【Abstract】 As a novel type of pile foundation, the investigation into the dynamic characteristics of stiff composite piles holds substantial theoretical significance for geotechnical engineering. Grounded in the principles of soil dynamics and pile foundation vibration theory, this study systematically examines the vertical displacement response at the pile head and along the pile shaft of stiff composite piles embedded in viscoelastic saturated soil layers under the influence of vertically incident seismic P-waves. Initially, a wave equation for saturated soil is formulated in cylindrical coordinates based on Biot’s porous medium theory. Subsequently, by integrating the vertical vibration equation for strength composite piles, a closed-form series solution for the longitudinal displacement of the soil skeleton is derived, leading to an analytical solution for the vertical displacement of strength composite piles under specified boundary conditions. Finally, through computational examples and parametric studies, this work elucidates the dynamic behavior of the interaction system between strength composite piles and saturated soil subjected to vertical seismic P-wave action at the pile tip. The findings indicate that moderately reducing the radius of the concrete core pile while increasing its length can enhance its vertical seismic resistance; conversely, during high-frequency stages, an increase in elastic modulus of the cement outer pile may detrimentally affect the seismic performance of strength composite piles. In designing these structures, it is recommended that the radius of concrete core piles be maintained within 40% to 60% of their total radius while setting their length to 20 to 40 times this radius. Additionally, it is advisable that the elastic modulus for cement outer piles be established at 2% to 5% relative to that of concrete core piles.更多还原