考虑横向惯性效应时饱和土中大直径桩的纵向振动研究

Vertical vibration of a large diameter pile with transversal inertia effect in saturated soil

基于饱和多孔介质理论,对均质饱和土中大直径桩的纵向振动特性进行了研究。利用Novak薄层理论和饱和土多孔介质理论获得大直径桩侧土体复刚度;根据桩侧土与桩连续接触条件,考虑横向惯性效应,将大直径桩等效为Rayleigh-Love杆,建立起大直径桩和土的耦合动力方程,利用Laplace变换求解大直径桩与土耦合动力方程得出均质饱和土中桩顶阻抗函数和导纳函数的解析解;利用卷积定理和Fourier逆变换得出桩顶速度时域响应函数的半解析解;最后分析了桩和土的相关参数对桩顶频域和时域响应函数的影响,并在低频范围内分析了相关参数对桩顶复刚度的影响,为饱和土中桩基的动力检测提供了新的理论依据。

Based on the saturated porous medium theory,vertical vibration of alarge diameter pile with transversal inertia effect in homogeneous saturated soil was studied. Firstly,the complex stiffness of surrounding soil was obtained with Novak's thin layer theory and the saturated porous medium theory. According to the continuous contact condition between the pile and surrounding soil,considering the pile 's transversal inertia effect,the large diameter pile was equivalent to a Rayleigh-Love rod,the coupled dynamic equations of the large diameter pile and soil were established. The analytical solutions to the impedance function and admittance function at the top of the pile were derived by solving the coupled dynamic equations of the large diameter pile and soil with Laplace transformation. Then,the semi analytical solution to the velocity response at the top of the pile in time domain was deduced with the convolution theorem and the inverse Fourier transformation. Finally,the influences of relevant parameters of the pile and saturated soil on the response function in frequency domainand that in time domainat the top of the pile were analyzed,and the influences of relevant parameters on the complex stiffness at the top of the pile within a lower frequency range were also analyzed. The results provided a new theoretical basis for dynamic detecting of piles in saturated soil.