Generalized axisymmetric continuous circle model for longitudinal vibration of large-diameter piles and its application

There exist two main deficiencies in the existing theoretical researches about the longitudinal vibration characteristics of large-diameter piles: (1) The pile models applied fail to consider sufficiently the three-dimensional (3D) wave effects of the pile body. (2) The dynamic characteristics within the low frequency range lack essential attention, which is much more important in practice. Regarding the two deficiencies, an innovative theoretical model called the generalized axisymmetric continuous circle model for investigating the longitudinal vibration of large-diameter piles is proposed. The pile is treated as the 3D continuous medium and the surrounding soil is stratified into several zones along the radial direction. The analytical solutions for the complex stiffness of the pile top are obtained by applying the coupled conditions between the adjacent soil zones and those at the pile-soil interface. After its rationality is verified, the proposed model is used to study the vibration characteristics of the large-diameter piles within the low frequency range. The laws and mechanisms of the construction disturbance effects are specifically discussed, and several new phenomena and useful conclusions are obtained, which may support a much more complete theoretical basis for the dynamic design and bearing capacity analysis of large-diameter piles.