考虑桩土耦合作用时桩基扭转振动特性研究

假设桩周土层为均质线性粘弹性体,土材料阻尼为粘性阻尼,桩为竖直弹性均匀圆形截面桩,从三维轴对称角度,对考虑桩土耦合作用时桩基扭转振动桩顶频域振动特性进行了理论研究。利用拉普拉斯变换,首先通过对土层进行求解得到其振动扭转角位移形式解,然后利用该解并以小应变条件下桩土接触界面位移连续来考虑桩土的耦合作用,来分析基桩的动力反应,研究得到了考虑桩土耦合作用时桩顶扭转频域响应函数的解析解。基于所得解对桩土系统的扭转振动特性进行了对比和分析,并重点探讨了桩侧土粘性阻尼对桩顶响应的特殊影响,校验了基于平面应变假定桩基扭转振动理论解的精确性。

SOIL-PILE INTERACTION IN TORSIONAL VIBRATIONS OF A PILE IN VISCIOUS DAMPING SOIL LAYER

Assuming that soil is uniform and linear and the frequency-domain torsional response of a viscoelastic layer with viscous damping, soil-pile interaction dynamically loaded pile in the soil layer are theoretically investigated. By Laplace transformation, the soil layer is studied first and the vibration displacement solution with undecided constants of soil layer is used in the analysis of pile response. And the corresponding solution of the displacement and velocity response functions at the pile head in frequency domain and the dynamic stiffness of pile are obtained in closed forms. A parametric study is conducted to determine the main features of the soil-pile interaction, and the special influence of viscous damping of soil layer is also discussed. Finally, a comparison between the theories based on plane strain assumption and the solution developed in this paper is investigated.