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给出了稳态振动时,垂直受荷群桩在横观各向同性饱和层状土中动力阻抗计算的一般方法。首先,基于Biot饱和介质的三维波动理论,借助Hankel变换,得到横观各向同性饱和土轴对称动力问题的通解,利用通解,给出饱和土层在Hankel变换域内的精确动力刚度矩阵,进而构建出饱和土层在竖向柱面荷载作用下的动力Green函数;其次,根据桩-土界面的位移协调及平衡条件,利用Kynia的方法,建立了饱和地基-群桩纵向耦合振动的边界元-有限元方程,给出了垂直受荷群桩动力阻抗的计算公式。算例表明:场地土的各向异性及土层刚度的变化,对摩擦型群桩动力刚度的影响要远大于对端承型群桩的影响。
The general method of dynamic impedance calculation of vertically loaded group pile in transversely isotropic saturated layered soil under steady state vibration is given. First, based on the three-dimensional wave theory of Biot saturation medium, the general solution of axisymmetric dynamic problem of transversely isotropic saturated soil is obtained by means of Hankel transform. By using general solution, the exact dynamic stiffness matrix of saturated soil in Hankel transform domain is given, The dynamic Green’s function of saturated soil under vertical cylindrical load is obtained. Secondly, according to the displacement coordination and equilibrium conditions of pile-soil interface, the boundary element of longitudinal coupling vibration of saturated soil-pile group is established by Kynia method. The finite element equation is given, and the formula of the dynamic impedance of vertically loaded group pile is given. The results show that the anisotropy of soil and the change of soil stiffness have a greater influence on the dynamic stiffness of the frictional grouping pile than that of the pile group on the opposite end.