Temperature Deformation Of CRTS ? Track Slab And Its Impact On Dynamic Responses Of Vehicle-track-bridge System

CRTS II slab ballastless track is widely used in the high-speed railway in our country. However, the gap is found between the track slab and the CA mortar layer during the construction process, which is caused by the non-uniform temperature gradient in the thickness direction of track slab. The gap will be a threat to the train running safety in the service stage. So the temperature warping deformation of track slab and its impact on the dynamic response of vehicle-track-bridge system are studied in this paper, from the statics and dynamics of CRTS II slab ballastless track. And the main research work and innovation points are as follows.(1) Research about the temperature effect and the dynamic analysis of CRTS? slab ballastless trackThe research status about the development of ballastless track, the temperature effect of slab ballastless track and the coupled vibration of vehicle-track-bridge system is summarized. And the problems are pointed out in the study on the temperature warping deformation and the impact on the dynamic response.(2) Establishment and verification of the finite element model about CRTS? slab ballastless track, and the influence analysis of factors on the temperature deformationThe components and the corresponding connections of CRTS II slab ballastless track are simulated by the finite element software. The model is validated. In order to obtain the actual temperature data, the temperature measurement of track slab is carried out. The influences of factors on the temperature deformation are analyzed, such as the dead load, the temperature-time effect of CA mortar layer and supporting layer, the worst condition, the initial temperature and the longitudinal link.(3) Temperature deformation mechanism of track slab under the temperature gradient and the overall temperature changeOn one hand, the warping deformations are compared under three different ways to apply the temperature load, by using the finite element software. On the other hand, the axis deformation, the bending deformation and the temperature deformation are cognized from the strain, and the vertical displacements of two structures at mid-span are derived under the temperature gradient and the overall temperature change, by formula deduction.(4) Extension of vehicle-bridge coupling vibration theory to the vehicle-track-bridge system about CRTS II slab ballastless trackMotion equations of the vehicle are established based on rigid-body assumption and D'alembert's principle. Motion equations of the track and the bridge are directly established using finite element method. The rail irregularities are taken as excitation of vehicle-track-bridge system. The vehicle and the track are connected by the vertical wheel-rail contact model. Thus the dynamic equilibrium equations of vehicle-track-bridge system are obtained, which can be solved with the Direct Coupling Method, the In-time-step Integration Method or the Inter-system Iteration Method based on Newmark-? numerical integration method.(5) Two new linear-approximation Hertz connect models and their validation,the secant and the tangent linear-approximation model, and the influence analysis of four vertical wheel-rail connect models on vehicle-track systemThe linearized Hertz connect model which is directly applied and not verified, is modified. Two new linear-approximation Hertz connect models, the secant and the tangent linear-approximation model, are put forward and proved. The wheel-rail force expressions under the two new models are unified and the wheel-rail contact stiffness of the two new models is derived. The additional dynamic matrices of vehicle-track system are respectively deduced under Hertz nonlinear contact theory, the displacement corresponding assumption, the secant and the tangent linear-approximation model. The influences of four vertical wheel-rail connect models on vehicle-track system are analyzed from the dynamic response, the adaptability condition about time step, the spectrum analysis of wheel-rail vibration and the wheel-rail connect stiffness.(6) Establishment of nonlinear track dynamic analysis model which corresponds to the temperature warping deformation condition, and the impact analysis of the additional track geometry irregularity and the track stiffness irregularity on the dynamic response of vehicle-track-bridge systemThe nonlinear track dynamic analysis model which corresponds to the temperature warping deformation condition is established whose connection springs between track slab and CA mortar layer are only compressed. The rail deformation caused by temperature warping of track slab is taken as the additional track geometry irregularity to analyze the impact on the dynamic response. The temperature warping of track slab is taken as its existing static deformation for dynamic analysis and it leads to the track stiffness irregularity to analyze the impact on the dynamic response.