Impact Of Temperature Effect On Bridge-based CRTSⅡ Slab-type Ballastless Track And Train Operation

CRTSⅡ slab-type ballastless track structure is one of the main types of high-speed railway construction in China,which has the characteristics of strong stability,uniform stiffness,high smoothness,and low maintenance.However,because the overall structure is mostly composed of concrete structures,due to the poor thermal conductivity of the concrete itself,the slab ballastless track structure is greatly affected by temperature effects,and temperature damages will occur under the effect of temperature gradient loads,such as overarching,warping,and cracking.The article takes CRTSⅡ slab-type ballastless track structure on the bridge as the research object,analyzes the deformation and stress of the structure under the temperature effect.The resulting structural deformation is added to the vehicle-trackbridge coupling system in the form of additional track irregularities,and the effect of temperature effects on train operation is further studied.The main tasks completed are as follows:(1)Based on the basic theory of thermodynamics and atmospheric physics,the heat absorption,transfer and distribution of the slab ballastless track structure on the bridge are explained,and the basic mechanism of the finite element is used to explain the temperature mechanism of the track plate.According to the basic equations of thermoelasticity,the calculation formulas of the deformation and stress of the track plate under the effect of temperature are deduced.(2)A finite element model of CRTSⅡ slab-type ballastless track structure was established using finite element software,and the effects of different factors on the temperature deformation of the track slab were investigated during simulation analysis.At the same time,three climate-representative cities in China were selected to analyze the difference of track slab deformation under linear and nonlinear temperature gradient loads.(3)Finite element model of prestressed concrete box girder is established.The box girder and the slab ballastless track structure are connected as a whole through a contact unit.The deformation of the track structure subjected to temperature effects is analyzed and the deformation data reflected on the top surface of the rail is extracted.(4)Use the multi-body dynamics software Universal Mechanism to establish a vehicle-track-bridge system model,and add the rail top deformation data to the rail in the form of additional track irregularities.The dynamic response of the vehicle under normal and superimposed temperature deformation conditions is analyzed.At the same time,from the perspective of train running safety and stability,the dynamic response of the cars at different operating speeds under high temperature conditions is analyzed.The results show that the safety and stability of train operation will be threatened with the increase of train running speed,so the train should take appropriate speed limit measures under high temperature conditions.