Mechanical Response Analysis Of Ballastless Track Considering Viscoelastic Characteristics Of CA Mortar

The prestressed track slab and concrete base plate of CRTS-I slab ballastless track are bonded into a complete force through the CA mortar filling layer.In the actual working process of the track structure,it plays the role of supporting the track plate,the load of the buffer train and blocking the crack propagation.It is the key functional layer in the track structure,its performance determines the comfort and durability of the structure.At present,there are few studies on the CA mortar layer,and many diseases such as seams and blocks appear in the service process of CA mortar,which a serious threat to the stability and the safety of the train.Therefore,it is of great significance to study the influence of CA mortar on slab track structure.In this paper,through the laboratory single axle static load compression creep test,that we can obtaine the experimental curves of viscoelastic characteristics of CA mortar materials.The viscoelastic properties of CA mortar are defined in the CRTS-I type slab track finite element model by Prony series,Study in the mortar layer elastic constitutive model and viscoelastic constitutive characteristics of dynamic response of structures under different.The viscoelastic model of CRTS-I slab track with initial damage is analyzed,and the mechanical response of the structure under initial damage is analyzed.The main contents and conclusions are as follows:Based on the uniaxial static compression creep test,the experimental curves of viscoelasticity of CA mortar at different temperatures were obtained.The test results show that the variation trend of creep characteristic curve is basically the same at different temperatures,the vertical displacement of CA mortar specimen increases with the increase of temperature,and the viscoelastic curve is fitted with Burgers and modified Burgers model.The fitting results show that the two models can simulate creep deformation characteristics of CA mortar well.The finite element software is used to simulate the compression creep test process.From the numerical simulation results,the modified Burgers model is more advantageous in characterizing the compression creep properties of the CA mortar.Through reasonable mechanical simplification and adjustment of material properties of CA mortar,a viscoelastic model of CRTS-I slab track on roadbed is established.The difference between the dynamic characteristics of the elastic track structure and the viscoelastic track structure is explored.The results show that the deformation and stress spatial distribution of the track plate and the base plate are basically the same under the different constitutive elements of the CA mortar layer,but the stress and displacement results obtained by the viscoelastic constitutive are all larger than the results of the elastic constitutive calculation.By establishing a model of CRTS-I type plate orbital viscoelastic model containing damage,the dynamic characteristics of the structure under the failure of the CA mortar layer,the attenuation of the block and the properties attenuation of the mortar material and the coupling failure of the block are explored.The results show that the maximum vertical dynamic stress of CA layer will increase by 4.4 times at the same time when the performance of CA mortar material decreases and the void failure occurs.