Study On Temperature Field Characteristics And Effect Of CRTS Ⅰ Slab Ballastless Track In Northeast Cold Region

Harbin Dalian High Speed Railway is located in the northeastern cold region.As part of the comprehensive action of complex climatic and train loads,numerous diseases occur in the track structure,especially the intermediate layer damage,The service environment of the Harbin Dalian High Speed Railway is characterized by low temperature and high temperature differences.The temperature field and the temperature effect of the track structure have obvious regional characteristics.Therefore,it is of great significance to explore the characteristics of temperature field of track structure in northeast cold area,analyze the most unfavorable temperature load conditions,and study the influence of interlayer damage and separation joint size on track structure performance,so as to carry out ballastless track structure design,performance analysis and determine maintenance tools in Northeast cold area.The main research contents and conclusions are as follows:(1)Based on the existing meteorological data in Northeast China,a three-dimensional solid transient temperature field analysis model of CRTS I slab ballastless track structure is established.Four extreme conditions of the hottest weather,the coldest weather and the maximum temperature difference in recent 20 years are applied to study the temperature field distribution characteristics of slab ballastless track structure.The results show that Without a frantic jumble of track structure within the temperature distribution along the depth direction is nonlinear,vertical transfer exist hysteresis temperature,different temperature,the depth change form an envelope,presents the "funnel",0-0.2 m depth range is area larger temperature difference of track structure,track structure temperature a significant turning point in the CA mortar layer,the CA mortar has the thermal barrier.The lateral temperature distribution of the track slab shows that the range of 0-0.3m around the slab edge is the area with large daily temperature variation.(2)According to the temperature distribution of the track slab,the vertical and lateral temperature gradients of the track slab under the most unfavorable weather conditions under different working conditions are studied,and the sensitivity of the influence of various meteorological factors to the temperature field of the track slab is further analyzed.The research shows that the difference between the positive and negative vertical temperature gradients of the track slab reaches 123.19℃/m and 100.28℃/m when the two daily temperature differences are the largest,109.08℃/m when the weather is the hottest,and 61.45℃/m when the temperature is the coldest.,The maximum vertical temperature gradient of the track slab occurs in the spring when the temperature difference is the largest;the lateral temperature gradient of the track slab is larger within 0.3m from the edge of the slab,which is 4 times the temperature gradient at 1.2m.The temperature of the track plate is positively correlated with solar radiation intensity and temperature,and negatively correlated with wind speed.The temperature of the track plate is most sensitive to changes in solar radiation,and is slightly affected by changes in wind speed and temperature.Under the influence of different meteorological factors,the temperature of the track plate has the largest daily temperature difference.The weather changes are the most significant.According to three meteorological factors,the extreme climatic conditions that may exist in the severe cold region of the northeast were obtained.Under extreme climatic conditions,the maximum positive temperature gradient of the track plate reached 157.47°C/m,and the maximum negative temperature gradient reached 57.79°C/m.The difference between the positive and negative temperature gradient of the vertical plate reaches215.26°C/m.(3)According to the most unfavorable temperature gradient field results when the temperature difference is the largest,a sequential thermo-mechanical coupling analysis is used to establish a finite element model based on the surface cohesion model to characterize the contact between the track slab and the CA mortar layer to analyze the stress state of the CA mortar layer under temperature load And the damage distribution between layers,further study the effect of the size of the seam between the track slab and the CA mortar layer on the stress and deformation of the track structure.Studies have shown that the maximum normal stress,transverse shear stress and longitudinal shear stress of CA mortar under temperature load all appear at the corners of the slab,and there is a phenomenon of stress concentration at the corners,and the damage of the CA mortar starts from the corners.Extend to the slab end and the slab edge;under the action of temperature load,when the slab end separation width exceeds 0.6m and the slab edge separation depth exceeds 2mm,the vertical displacement between the track slab and the CA mortar layer increases,which affects the track structure Service performance.(4)The damage between track slab and CA mortar layer under the coupling action of train and temperature load is studied.The results show that: under the coupling action of the two loads,the indirect contact force between the CA mortar layer and the track slab increases significantly,but the damage degree of the track slab and the CA mortar layer is still small under the coupling action of the two loads in a short time.