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将地震液化场地土层分为非液化表层土、中部的液化土层和底部的基层,基于饱和多孔介质理论和Novak薄层法,研究轴向压力作用下液化黏弹性土层中端承桩的水平动力特性。利用Helmholtz分解和变量分离法,得到液化土层对桩水平振动的阻抗。利用矩阵传递法,在频率域得到轴力作用下液化土层中端承桩简谐振动的解析解和桩头复刚度的表达式,并进行参数研究,分析轴力、桩-土模量比、桩长径比、液-固耦合系数等对桩头动力刚度和阻尼的影响。结果表明,在轴力作用下,不同长径比、桩-土模量比、液-固耦合系数时的动力刚度绝对值均比无轴力作用时减小,但随频率的变化趋势相同;轴力对桩水平振动的动力阻抗影响显著,随着轴力的增加,桩的水平振动动力刚度因子的绝对值减小,若轴力继续增大,其绝对值趋近于0,桩发生失稳破坏;桩长径比和桩土模量比对桩的水平振动动力阻抗有显著的影响,而液-固耦合系数的影响较小。
Based on the theory of saturated porous media and the Novak thin layer method, the soil of the liquefied soil in the liquefied viscoelastic soil layer is studied based on the theory of saturated porous media and the method of Novak thin layer. Horizontal dynamic characteristics. Using Helmholtz decomposition and variable separation method, the impedance of liquefied soil to horizontal vibration of pile is obtained. Using matrix transfer method, the analytic solution of simple harmonic vibration of end bearing pile and the complex stiffness of pile head in liquefied soil under the action of axial force are studied in the frequency domain, and the parameters are studied. The effects of axial force, pile-soil modulus ratio , Pile aspect ratio, liquid-solid coupling coefficient on the dynamic stiffness and damping of pile head. The results show that under the action of axial force, the absolute values of dynamic stiffness at different aspect ratios, pile - soil moduli ratio and liquid - solid coupling coefficient decrease more than those without axial force, but the same trend with frequency. The axial force has a significant influence on the dynamic impedance of the pile horizontal vibration. With the increase of the axial force, the absolute value of the dynamic stiffness factor of the horizontal vibration of the pile decreases. If the axial force continues to increase, the absolute value of the axial stiffness approaches 0, The ratio of pile aspect ratio to pile-soil modulus has a significant effect on the dynamic impedance of horizontal vibration of pile, while the influence of liquid-solid coupling coefficient is small.