Study On The Substructure Model Of End Bearing Pile-Soil Dynamic Interaction In Frequency Domain

In recent years,with the rapid development of national economy,high-rise buildings,long-span bridges,offshore platforms and nuclear power plants and other major projects have been built,pile foundation are sometimes subjected to seismic load,wind load,traffic load,mechanical dynamic load and artificial excitation and other dynamic loads.In order to study the dynamic response characteristics and response law of this kind of structure more deeply and reasonably,and to predict and evaluate its seismic safety more correctly,it is necessary to use a reasonable pile-soil dynamic interaction analysis model to study the dynamic response of the structure deeply.In this thesis,the subject of pile-soil dynamic interaction is studied,focusing on the analytical expression of dynamic impedance of pile in foundation soil under horizontal vibration.Through theoretical analysis and numerical calculation,the mechanism of pile-soil dynamic interaction is deeply understood,providing guidance for practical application.It also provides some theoretical basis and design suggestions for seismic design considering dynamic interaction of soil foundation,pile foundation and superstructure.This thesis is divided into four chapters,mainly doing the following work:1.A three-dimensional frequency-domain substructure model for horizontal vibration response of end pile in radially inhomogeneous linear elastic single-phase soil is established.Firstly,the analytical solution of horizontal resistance of homogeneous soil is obtained according to boundary conditions.Furthermore,the boundary layer model and transfer matrix method are used to calculatethe dynamic impedance coefficient of the layer in the radial non-uniform boundary region.Then,the method was verified by the three-dimensional finite element model in ABAQUS software.Finally,the proposed model is used to analyze the effects of soil dynamic stiffness,soil damping,soil radial non-uniformity and other parameters on the dynamic response of the structure,and the effects of uniform and non-uniform ground motion excitation on the seismic response of the structure.2.Neglecting the inertial forces associated with the relative acceleration of pore fluid,the u-p analytical solution of dynamic impedance of horizontal vibrating pile in radial non-uniform saturated soil layer is derived by using boundary layer model based on Biot dynamic consolidation equation of saturated soil.Then,the rationality of the proposed method is verified by co MParing with the existing analytical solutions of u-w form.The influence of the soil shear modulus,permeability coefficient,porosity,radial inhomogeneity,pile radius and other parameters on the errors between u-p form and u-w form are investigated.Finally,the applicable range of the u-p approximation is given.3.Neglecting the inertial forces associated with the relative acceleration of pore fluid,a three-dimensional frequency-domain substructure model of the horizontal vibration response of end pile in radially inhomogeneous linearly elastic two-phase saturated soil is established based on the dynamic consolidation theory of saturated soil.Then,the influence of pile size,load frequency and other parameters on the errors between single-phase medium model and two-phase medium model under the concentrated load of pile top and horizontal ground motion of pile bottom is discussed respectively based on this model.The research work in this thesis enriched the method of dynamic response analysis of single-phase and saturated soil,and provided theoretical guidance and scientific basis for seismic design of dynamic interaction between soil foundation,pile foundation and superstructure.