中文摘要：

针对变截面群桩基础高墩的几何特性,将桥墩与群桩基础简化为空间整体,在考虑桥墩变截面特性及桩土相互作用的基础上,提出群桩基础变截面桥墩分析模型;将分析模型分解成群桩基础的刚体变形与桥墩的弹性变形两个部分,分别基于能量法与有限单元法求解相应的自振频率,并采用Southwell频率合成法,将整体计算模型表示成两个部分的合成,从而导出变截面桥墩的自振频率,通过算例证明该方法的实用性,并分析了桥墩参数对自振频率的影响,获及了一些定性的结论。结果表明,变截面高墩自振频率的计算分析中,桩-土相互作用的影响不容忽视,考虑桩土相互作用和桥墩本身的非线性更符合工程实际。

英文摘要：

Based on considering tapered pier behavior and the soil-pile interaction,bridge pier and group piles are simplified as global properties;and then an analysis model of tapered pier supported by group piles is presented;Secondly,analysis model is decomposed into two subsystems： elastic deformation of bridge pier and rigid deformation of group piles,the natural frequencies of which are solved by finite element method and energy method.Further,the global natural frequency of tapered pier is deduced by using the Southwell frequency composition method.Lastly,the comparison between calculated results and the real engineering examples shows that the method is reasonable;and the analysis results of the parameters of pier in natural frequency could be available for some reasonably conclusions.The results show that it is more practical in consideration of the pile-soil interaction and the geometry nonlinear of tapered pier.The influence of pile-soil interaction on natural frequency of tapered high pier could not be neglected in study.