Ballastless Track-subgrade Of High-speed Railway Under Dynamic Load Dynamic Response Analysis

In the 21 st century,high-speed railways have become a hotspot for the development of railways in the world as an efficient and sustainable public transportation.With the large-scale construction and opening of high-speed railways,various problems will arise in operation and maintenance.The dynamic response of high-speed railway ballastless roadbeds is very complex.Scholars at home and abroad have conducted many important studies,but they are still far away.Far from enough.Based on this,the dynamic response analysis of the track subgrade system has important reference significance for railway design,construction and operation.In this paper,the overall model of the high-speed railway ballastless track subgrade system is established.The dynamic load is achieved by applying a 350 km / h excitation force function curve for 10 s,and reading the structure’s vertical displacement,vertical dynamic stress,and vertical acceleration to perform Comparative analysis.The necessity of considering the viscoelasticity of CA mortar,the analysis of the influence parameters of the dynamic response index,and the changes in the track subgrade system in the presence of damage are discussed.The following results have been achieved:(1)CA mortar material and soil material are given two properties of elasticity and viscoelasticity respectively,which are combined in two,and a total of four groups of data are compared and analyzed.The dynamic responses of track slabs,base slabs,subgrades and other structures have changed,and the difference in the index of the track structure is particularly obvious;as the depth continues to increase,the vertical displacement,stress and acceleration of each structural layer caused by dynamic loads are gradually gradually Decay trend.The nonlinear properties of CA mortar and soil materials are factors that must be considered in structural analysis.(2)The effect of train speed on the vertical displacement of the track subgrade structure is not a simple positive correlation,but there will be a sudden change,that is,as the vehicle speed increases,the vertical displacement presents a distinct double-peak phenomenon.The relationship between the axle weight of the train and the various values of the track subgrade structure increases linearly.The effect of the wheel load on the track subgrade is obvious.The relationship between the stiffness of fasteners and the values of each index of the track subgrade structure increases linearly.The elastic modulus of the soil has little effect on the values of each index of the track subgrade structure.(3)The influence of CA mortar degradation on ballastless track subgrade system is not great.As the degree of degradation increases,vertical displacement and vertical acceleration tend to increase,while vertical dynamic stress decreases.The impact of CA mortar falling block is large,and the maximum vertical dynamic stress around the void area is 3.4 times normal.There are some limitations to the effects of uneven bed packing.The effect of partial emptying of the foundation bed is very strong.Under normal circumstances,the vertical dynamic stress of the surface of the foundation bed is 3 times that of the emptying.