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考虑土体三维波动效应和桩–土耦合振动,把桩看作一维杆,把土体看作三维轴对称黏弹性介质,对黏弹性地基中现浇大直径管桩纵向振动频域特性进行了理论研究。首先通过引入势函数对土体振动方程解耦,采用Laplace变换和分离变量的方法求得了桩周土及桩芯土频域响应解析解,进而利用桩土完全耦合的条件得到桩振动响应解。将所得解完全退化到实心桩的解,验证了解析解的合理性,并与未考虑三维效应的简化解对比。分析了桩底刚度系数、桩长以及桩径等对桩顶复阻抗的影响,得到了各参数对桩振动特性影响的规律。分析表明:桩底刚度系数增大,共振频率增大,且复阻抗的振荡幅值增大。无桩芯土时复阻抗的振荡幅值比桩周桩芯土都存在时大,无桩周土时复阻抗的振荡幅值比无桩芯土时大。桩长增大,桩顶复阻抗的振荡幅值和共振频率均显著减小,当桩长增大到一定长度的时候,增加桩长对桩顶复阻抗基本没有影响。外径增大或内径减小,桩顶复阻抗的振荡幅值增大。
Considering the three-dimensional wave effect of soil and coupling vibration between pile and soil, the pile is regarded as a one-dimensional bar and the soil is considered as a three-dimensional axisymmetric viscoelastic medium. The longitudinal vibration frequency-domain characteristics of large diameter pipe pile cast in viscoelastic foundation Theoretical research. Firstly, by introducing the potential function, the vibration equation of soil is decoupled and the analytic solution of the frequency response of the soil around the pile and the pile core is obtained by Laplace transform and separation variables. Then the pile vibration response solution is obtained by the complete coupling of pile and soil. The complete degenerate solution of the solution to the solid pile solution verifies the rationality of the analytical solution and compares it with the simplified solution without considering the three-dimensional effect. The influence of the pile bottom stiffness coefficient, pile length and pile diameter on the complex impedance of the pile top is analyzed, and the law of the influence of each parameter on the pile vibration characteristics is obtained. The analysis shows that the stiffness coefficient of pile bottom increases, the resonance frequency increases, and the amplitude of complex impedance increases. The amplitude of the complex impedance is larger than that of the pile around the pile during the absence of pile-core, while the amplitude of the complex impedance is larger than that of the pile-free core. When pile length increases, the oscillation amplitude and resonance frequency of pile top complex impedance decrease significantly. When pile length increases to a certain length, increasing pile length has no effect on pile top complex impedance. As the outer diameter increases or the inner diameter decreases, the oscillation amplitude of the complex impedance at the top of the pile increases.