Research On Dynamic Response Of Ballastless Track-Subgrade Under High-Speed Train Load

With the rapid development of society and economy,high-speed rail has developed rapidly in my country due to its characteristics such as fast speed,stability and comfort,large passenger capacity,and safety and economy.In order to ensure that trains can run at high speed and smoothly,it is bound to be more demanding on the track subgrade structure.Provisions.The design of high-speed railway subgrade mainly considers the strength and rigidity of the subgrade and the stability of the train under long-term operation.Especially due to the substantial increase in train speed,the subgrade will bear greater dynamic load and produce larger additional deformations,thereby affecting the normal operation of the train.In this paper,based on the moving loads of high-speed railway trains and the structural characteristics of the slab ballastless track subgrade system,based on previous studies,theoretical analysis and finite element numerical simulation analysis are used to study the dynamic response law of ballastless track subgrade,and mainly achieved the following research results:(1)Systematically compare the advantages and disadvantages of the existing traintrack-subgrade numerical calculation model,and combine the characteristics of the existing single-track high-speed railway ballastless track structure,and referring to the theory of triplestack composite beam theory,the beam unit and the spring-damping unit are coupled to establish a high-speed railway Slab ballastless track-subgrade coupled vibration model;(2)The dynamic response of the track-subgrade structure of the high-speed train is analyzed by time-domain finite element analysis.Based on the field test data of the subgrade dynamic response under the load of the EMU during the "joint adjustment and test" stage of the Wuhan-Guangzhou high-speed railway,the spatial distribution characteristics of the dynamic stress and dynamic displacement of each structure layer of the subgrade along the vertical,horizontal and line running directions of the subgrade are obtained.(3)Comprehensively consider the influence factors of the dynamic response of highspeed railways,and analyze the dynamic response distribution of train speed,slab track structure parameters,and subgrade structure parameters to the dynamic response of railway embankment through the ballastless track-embankment-foundation dynamic coupling numerical model established above the influence range and influence degree of the law provide references for actual engineering;(4)Study the cumulative deformation characteristics of saturated clay under cyclic loading,based on the existing long-term settlement calculation method of high-speed railway subgrade,by simulating the effect of soil on cyclic loading.The attenuation of lower stiffness and the empirical formula calculate the long-term settlement of the roadbed,and discuss the distribution law of the long-term settlement of the roadbed in the roadbed,which is of great significance for improving the structure of the roadbed.