Analytical Models And Solutions For Longitudinal Vibration Of A Floating Pile In Viso-Elastic Soils Considering The Pile-Soil Interface Sliding

As a widely used pile type,the research on the longitudinal vibration theory of floating pile is of great practical significance for the design of anti vibration of pile foundation and the development of dynamic pile testing technology.The key to the longitudinal vibration of floating piles lies in how to reasonably simulate the interaction between the pile and the surrounding soil.In this paper,the existing model of virtual soil pile is improved.Based on the Kelvin model,considering the pile-soil interface sliding,the analytical solutions of dynamic impedance and velocity response of floating pile top in homogeneous and layered soil are solved.The main research contents are as follows:(1)Considering the pile-soil interface sliding,the coupling model of pile-soil longitudinal vibration in.homogeneous foundation is established.The analytical solution of dynamic impedance and the semi analytical solution of velocity response in time domain are obtained by using the analytical method,and then the solution in this paper is reduced to the existing solution to verify its rationality.On this basis,the influence of the parameters on the vibration of the floating bearing pile is analyzed,including the stiffness coefficient of the interface between pile side soil and the real pile,the pile length of the real pile and the virtual soil pile,the shear wave velocity of pile side soil and pile subsoil.The results show that the pile-soil dynamic sliding model is more reasonable to consider the interaction between pile and soil than the fully coupled model,and the model in this paper has better advantages in the application of the analysis of the longitudinal vibration characteristics of floating bearing piles.(2)Based on the coupled model of pile and soil in homogeneous foundation,the coupled model of pile and soil in layered.foundation is established,and the analytical solution of dynamic impedance of floating pile top and the semi analytical solution of velocity response in time domain are obtained by considering the pile-soil interface sliding and the method of dynamic impedance transfer.Starting from the stratification of pile side soil and the defect of the real pile,this paper analyzes the influence of the parameters on the longitudinal vibration of the floating bearing pile,including the rigidity coefficient of the interface between pile side soil and the real pile,the shear wave velocity of pile side soil,the thickness and modulus,the length of the real pile,the reduction and expansion of the real pile diameter,and the length and location of the defect.(3)In this paper,the dynamic response of pile top based on the three-dimensional axisymmetric model of soil mass is compared with the results of the plane strain model of soil mass.Then the influence laws of the interface stiffness coefficient between pile side soil and the real pile,the elastic wave velocity of the real pile,the length of the real pile,the shear wave velocity of pile side soil,the shrinkage and expansion of the real pile on the longitudinal vibration characteristics of the floating bearing pile are analyzed in different frequency ranges.The results show that in the low frequency range,the plane strain model of soil mass will have a large error,so the three-dimensional axisymmetric model of soil mass should be used.