层状地基端承桩扭转动力阻抗研究

本文采用Novak薄层法推导粘弹性地基的扭转动力阻抗,并将其用于考虑桩土相互作用的单桩扭转动力阻抗,又通过传递矩阵法将此公式推广到求取层状地基单桩扭转动力阻抗。而且本文以工程中常用的端承桩为例,推导了层状地基中端承桩扭转动力阻抗的简化计算公式。根据此公式,分析了频率、上覆软土层厚度、上覆软土层刚度等因素对单桩扭转动力阻抗的影响,分析结果表明,随着振动频率提高,层状地基中端承单桩的扭转动力阻抗的实部有缓慢下降的趋势,而虚部则增大;随着上覆土层厚度的增加,层状地基中端承单桩的扭转动力阻抗的实部和虚部均减小;随着上覆土层刚度的减小,层状地基中端承单桩的扭转动力阻抗的实部减小,虚部在低频段减小,而在较高频率段则增大。

Research on torsional dynamic impedance of end-bearing pile in layered soils

Novak layer method which was appliesd to compute the dynamic impedance of torsional vibration for layered soils is introduced to analyze the torsional dynamic pile-soil interaction.The computing formula for torsional dynamic impedance of single pile in layered soils is got by transfer matrix.Furthermore,according to the end-bearing pile which is usually applied to engineering,the simplified formula for torsional dynamic impedance of end-bearing pile in layered soils is obtained.On the basis of this formula,the effect of frequency,and thickness and stiffness of topsoil on the torsional dynamic impedance of single-pile is analyzed.The results show that the real and imaginary parts of the torsional dynamic impedance of end-bearing pile in layered soils decrease along with the augment of the thickness of topsoil;the real part of the torsional dynamic impedance for end-bearing pile in layered soils decreases and the imaginary part of the torsional dynamic impedance for end-bearing pile in layered soils heightens along with the increase of frequency.When the stiffness of topsoil is diminished,the real part of the torsional dynamic impedance of end-bearing pile in layered soils reduces.