| With the continuous development of China’s economy in recent years,the travel mode of Chinese residents has shown obvious changes compared with the previous ones.Currently,taking rail transit has become the main way for people to travel.Because of the rail transit will inevitably produce the corresponding vibration in the process of driving influence,in the process of running on the surrounding environment of the vibration problem has gradually become the security issues of cannot be ignored,it will affect the settlement of ground important buildings,scientific rese arch and production of high precision instruments and equipment used in life,so the vibration generated by the study of rail transit has certain necessity and urgency.In this paper,the dynamic response analysis of tunnels under moving loads was carried out on the basis of relevant theories of elastic dynamics and Biot theory and the corresponding transformation method by Fourier.The main research contents of this paper are as follows:1.The dynamic response of elastic soil under point load was studied by analytical method.By using Hankel and Fourier transform,the general solutions of displacement,stress and pore pressure are derived from the potential functions of solid s keleton and pore fluid and the governing equations of The Biot theory.The transmi ssion matrix of the interface is obtained by using the general solution and the continuous condition at the boundary of the tunnel.The transmission matrix method of layered porous media is mainly based on the basic transmission matrix method,boundary conditions and point force or fluid point source action.The transmission matrix method of layered porous media is used to obtain the basic solutions of point forces and point sources in frequency domain and time domain.Through numerical analysis,the dynamic response of layered porous half-space under point load is analyzed.2.The dynamic response of elastic soil under impact load is studied by analytical method.The vibration problem of two-dimensional elastic layer surface when point load moves along the beam is studied theoretically.Assume that the layer has a low viscosity,is fixed along the bottom,and has a traceless surface.The euler-Bernoulli model is used to describe the beam,and the beam is parallel to the surface and the bottom part.The surface vibration under three loads,namely constant load,harmonic load and stationary random load,is analyzed.The vector displacement and vibration amplitude spectrum of a certain observation point on the tunnel surface are analyzed under deterministic loads.For random loads,the main attention is paid to the vibration change at the observation point.Through the kinematic analysis of wave propagation in the structure,the qualitative characteristics of the results are analyzed.3.The dynamic response of elastic soil under moving line load is studied by analytical method.By moving at a constant velocity parallel to the surface of the half-space,the dynamic dislocations and stresses generated by surface line loads in the multi-layer viscoelastic half-space can be calculated using the Fourier transform of the frequency response,which in turn can be obtained by analyzing the integral over the horizontal wave number.In terms of generalized transmission and reflection coefficients,the effect of layering can be included by using an exact decomposition of the displacement and stress fields.By comparing the existing research results,the performance in uniform half space is compared,and the numerical results of surface load and stress displacement and stress field in half space are given.4.The dynamic response of elastic soil under moving line load is studied analytically.By using the Fourier transform method,the solution of the frequency-wavenumber domain of the tunnel under the action of continuous moving load is obtained through calculation and analysis of the boundary conditions of the tunnel.The conditions of the tunnel under the moving load are obtained by Fourier transform. |
