| CRTSⅡ type plate ballastless track is widely used in high-speed railroad construction because it has good integrity and high laying accuracy,which makes trains have higher smoothness when running at high speed.However,due to factors such as construction quality,complex environment and increasing service time,the bearing layer of CRTSⅡ type ballastless track in roadbed section starts to deteriorate,which brings certain threat to the safe operation of high-speed trains.In order to analyze the damage change of bearing layer deterioration and the influence on the mechanical performance of track structure,this paper drills core samples of bearing layer material from the field and carries out uniaxial compression test research;Using the test results and based on the material plastic damage intrinsic structure model,the finite element software ABAQUS is used to establish the static performance analysis model of CRTSⅡ slab type ballastless track in roadbed section and analyze the static performance of CRTSⅡ slab type ballastless track under the overall temperature and temperature gradient load.Finally,using ANSYS/LS-DYNA explicit dynamics software,we established the vehicle-roadbed section CRTSⅡ slab ballastless track vertical coupling dynamics model.We studied the influence of bearing layer deterioration on the dynamic service performance of the track.The main contents and conclusions are as follows.(1)The concrete of the bearing layer has local problems of uneven distribution of coarse aggregate,honeycomb porosity and poor bonding of coarse and fine aggregate;Because the concrete core samples are taken from the upper and lower part of the bearing layer,the bearing layer is divided into upper and lower layers.The uniaxial compression test results show that: the overall concrete strength of an upper layer of bearing layer is smaller than that of a lower layer.The strength of the under-rail bearing layer is smaller than that of the middle of the plate,and there are also some differences between the bearing layers of different sections.Among them,the strength of the core samples of the upper layer of the bearing layer corresponding to the two under-rail positions is 7.50 MPa and 10.39 MPa,respectively.The strength of the lower layer of the bearing layer in the plate is 16.67 MPa and 21.69 MPa,respectively,with the difference reaching 9.17 MPa and 11.30 MPa,respectively,which are more than 50% of the maximum value.Therefore,the CRTSⅡ type plate ballastless track service,Therefore,it is necessary to consider the influence of the difference in strength between the upper and lower layers of the bearing layer in the performance analysis.(2)The deterioration of the bearing layer material performance makes the static service performance of the track structure differ significantly from the design condition,which causes different degrees of increase in the indexes of bearing layer damage,longitudinal stress of the track plate and vertical displacement of the bearing layer;When the overall temperature changes by 50 ℃,the maximum compression damage of the bearing layer increases by 0.147 after the deterioration of the bearing layer compared with the ideal condition,which is 5.6 times of that before the deterioration.The maximum vertical displacement increased by 0.16 mm,which was46% of that before the damage;The maximum vertical displacement of the support layer increased by 0.23 mm,which was about two times of that before the deterioration;So the deterioration of the support layer under the effect of the overall temperature had a greater effect on the pressure damage of the track structure,the vertical displacement of the track plate and the support layer.Under the gradient temperature of the track structure surface temperature of 50 ℃,the longitudinal stress of the track plate increases by 0.11 MPa after the deterioration of the support layer relative to the ideal condition,and the vertical displacement of the track plate and the support layer is unchanged;So the track structure is less affected by the deterioration of the support layer under the action of the gradient temperature.Under the overall temperature change of 50 ℃ and trainload,relative to the ideal condition,the maximum compression damage of the bearing layer increased by 0.155 after bearing layer degradation,which is about 5.3 times of that before degradation;The longitudinal stress of the track plate is almost unchanged,and the maximum vertical displacement increased by 0.13 mm,which is 11 % of that before degradation;The maximum vertical displacement of bearing layer increased by 0.16 mm,which is12 % of that before degradation.Therefore,the overall temperature and train load-bearing layer damage is seriously affected by the bearing layer deterioration.Under the action of gradient temperature and trainload with a surface temperature of track structure at 50 ℃,the damaged area and depth of bearing layer increase after bearing layer deterioration compared with an ideal condition;The longitudinal stress of track plate increases by 0.16 MPa;The vertical displacement of track plate and bearing layer is unchanged,so the deterioration of bearing layer under the action of gradient temperature and trainload increases the damaged area and depth of track structure,and other effects are smaller.Other effects are smaller.(3)With the increase of bearing layer deterioration,the maximum vertical displacement of rail and track plate increased by about 0.44 mm and 0.45 mm respectively,which increased by 60 % and 62 % respectively compared with the pre-deterioration;The deterioration of bearing layer increased the deformation of track structure.After the deterioration of the bearing layer,the vertical vibration acceleration of the car body,bogie,wheelset and track plate decreases.The wheel weight reduction rate also decreases,and the deterioration of the bearing layer does not affect the stability and safety of the car body,considering the vertical vibration acceleration and wheel weight reduction rate of the train studied in this paper. |
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