Analysis On Dynamic Response And Settlement Of CRTS Ⅲ Ballastless Track Subgrade On High-speed Railway

High-speed railway has become the inevitable choice for China’s modern transportation and the core technology for independent research and development.With the continuous development of high-speed railways,ballastless track is an important part of the line structure,and is also advancing with the times.The CRTS III type ballastless track is currently China’s newest type of self-innovation plateless ballastless track.Due to the extremely wide range of high-speed railways in China,it will inevitably go through soft soil areas.At present,research on high-speed railways built on soil roadbeds is not enough,and high-speed railways built in soft soil areas are rare.The normal service of ballastless track is very strict on the roadbed.Therefore,it is necessary to study the dynamic response of the ballastless track in the high-speed railway area.In this paper,firstly,the dynamic triaxial tests of soft soils collected from the site are carried out.It is found that under the cyclic loading,the cumulative plastic strain in the soil increases with the increase of the number of loads.The calculation model proposed by Chai and Miura can be well fitted to the cumulative plastic deformation and vibration frequency curve.Then through the analysis of the train load,take the action of the excitation force to simulate the traffic load of the train,and use ABAQUS finite element software to establish the ballastless track-subgrade dynamic response analysis model.The ABAQUS/Explicit solver module was used to calculate the dynamic response of the subgrade.The results show that the dynamic response of the subgrade is the strongest on the subgrade and stress concentration occurs on both sides of the track slab.On this basis,through the dynamic analysis and comparison of the modulus of each structural layer of subgrade,the influence of material parameters on the dynamic response of subgrade is obtained,which provides a basis for the dynamic optimization of subgrade.After analyzing the dynamic response of the subgrade,it can be found that the dynamic stress in the soil foundation is sufficient to cause plastic deformation of the soil.Therefore,the cumulative deformation calculation model is used to analyze the subgrade settlement law.The results show that the cumulative plastic strain in the soil decreases with depth and increases with the increase of the number of loads.In the early stage of train operation,the cumulative deformation rapidly accumulates,and with the increase of the number of loads,the growth rate of cumulative deformation gradually decreases.In terms of distribution of the cumulative deformation of the cross section of the roadbed perpendicular to the track direction,the train load has a certain range of influence on the surrounding soil.