Study On The Dynamic Response Of High-speed Railway And Foundation

With the rapid development of the high-speed railway in China,the vibration problems of track structures and foundation caused by the moving train load have been widely concerned.When the train load meets certain conditions,it will cause the violent vibration of the surface of the foundation and endanger the safety of the driving.Therefore,the dynamic response caused by the moving load on the track structure of the high speed railway and foundation was studied in this paper to provide some references for the design and operation of the high speed railway.The high-speed railway structures were simplified as triple Euler-Bernoulli beams model in this paper.Considering the limitation of the Winkler foundation,the foundation was regarded as a Pasternak double parameters foundation.The governing equations of the triple beams on the Pasternak foundation were solved by Fourier transform and the residue theory.The influences of load frequency,load speed,damping and stiffness coefficient of the system and shear force on displacement,shear force and bending moment of the triple beams were analyzed respectively.The actual foundation soil is usually stratified.Therefore,the TRM method combined with fast Fourier dynamic was used to slove the response of the triple Euler-Bernoulli beams and the layered elastic foundation to consider the stratification of the foundation.The displacement and stress of any point inside the elastic layered foundation were obtained.The influences of velocity,frequency and parameters of soil on the displacement of the ground surface were studied.The stress-strain relationship of foundation soil under train cyclic loading has obvious nonlinearity,hysteresis and strain accumulation.In order to study the stress-strain relationship of the ground soil under the cyclic loading of the train and obtain the dynamic shear modulus and the damping ratio,the two-way vibration triaxial tests based on the original soft clay in Shanghai were carried out.The influence of lateral pressure coefficient,consolidation confining pressure,load frequency and stress path on dynamic shear modulus and damping ratio were studied.In order to further simulate the dynamic response of track and foundation under actual train loads,a three-dimensional finite element model of track-subgrade-foundation was established by ABAQUS.The variation of stress,displacement and acceleration at different position of track structure,subgrade and foundation under the moving train loads and the speed effect were obtained by using the dynamic display algorithm combined with infinite element.The influence of increasing velocity on stress,acceleration and displacement were studied.The differences between double track and single track were also compared.