Study On Vertical Vibration Characteristics Of Pipe Piles In Viscoelastic Single-phase Soil

Dynamic response analysis of a pipe pile considering soil radial inhomogeneity under vertical vibration load is presented.First of all,Dynamic wave eqrations of plane inhomogeneous soil and one-dimensional viscoelastic or elastic pile are constructed based on constitutive relations of soil and pile.Leading in boundary conditions and pile-soil contact condition,the dynamic equations are solved by analytical solution method.The dynamic interactions of pipe pile and inhomogeneous soil under vertical vibration load are systematically investigated.The principal contents are as follows:(1)Based on the basic theory of wave equation,Dynamic wave equations of one-dimensional elastic pipe pile and plane soil are constructed according to the definite solution problem.Based on that,the dynamic response of solid pile andpipe pile under vertical vibration load are studied.Mathematic programming is used to analysis curve fo pipe pile complex stiffness,then comparison with the results in related literature..(2)Considering the driving effect of pipe pile,the soil is assumed to be viscoelastic and radially inhomogeneous,by utilizing the plane strain model and combining the boundary condition,complex stiffness of the outer soils at the interface of pipe pile is derived by complex stiffness transfer method from outer zone to innier zone.Then,the pile is modeled as one-dimension elastic theory valid for pipe pile,the expression of the impedance function and frequency response function at pipe pile top are derived by solving the dynamic equation.Pipe pile-soil interactions and dynamic characteristics of soil are obtained by investigating the influences of soil inhonogeneity caused by construction.(3)The soil is assumed to be radially inhomogeneous and vertically layered.At first,complex stiffness at the interface of pile sections and soil is derived by complex stiffness transfer plane strain model,and the an analytical solution of dynamic response in frequency domain is derived by solving the dynamic equations in vertical layered and radially inhomogeneous soil are obtained by soil parametric analysis.