虚土桩扩散角对楔形桩扭转振动阻抗的影响

Influence of Cone Angle of Fictitious Soil Pile on Torsional Vibration Impedance of Tapered Pile

基于桩端土的锥形虚土桩模型,研究端土应力扩散效应对楔形桩扭转振动阻抗的影响。首先将桩侧土和桩端土划分多个薄层,采用平面应变模型求解得到桩(虚土桩)侧土的剪切复刚度,然后利用Laplace变换技术和阻抗函数递推法得到虚土桩顶部阻抗,并将其作为楔形桩的实际支撑刚度,进一步推得楔形桩桩顶扭转振动阻抗频域响应解析解;最后,分析虚土桩扩散角对楔形桩扭转振动阻抗的影响。研究表明:随着虚土桩扩散角的增大,楔形桩桩顶扭转动刚度逐渐增大,动阻尼逐渐减小。

Based on the tapered fictitious soil pile model, the torsional vibration impedance of tapered pile is investigated with the consideration of stress dispersion effect of pile end soil. First, the pile-soil system is divided into infinite segments, which is allowed for the stratification and variable cross-section of the tapered pile. The complex shear stiffness of pile surrounding soil is obtained by using the plain strain model. By means of Laplace transform technique and impedance function transfer method, the complex impedance at the top of fictitious soil pile is derived and then it is used as the real support stiffness of the tapered pile. Through further recursion, the analytical solutions of torsional dynamic response of a tapered pile in the frequency domain are derived. Finally, the influence of cone angle of fictitious soil pile on the torsional vibration impedance of tapered pile is analyzed. The result shows that ： with the increase of cone angle of fictitious soil pile, the torsional dynamic stiffness at the top of tapered pile increases, and the corresponding dynamic damping decreases gradually.