| Due to the impact and vibration of the train load,the ballast track structure commonly used in high-speed railways will cause gravel splashing during long-term operation,accompanied by a decrease in noise and performance.The emerging polyurethane curing track bed can solve the deterioration problem and reduce the track bed deformation,but its cost is high.Asphalt-cured track bed material mixed with rubber particles is sustainable and economical,and can be used as an alternative material.In this paper,the asphalt mortar based on the corresponding solidified track bed material is taken as the research object,and its crack resistance performance is comprehensively evaluated by semicircle bending test,combined with acoustic emission technology and discrete element simulation method,and the asphalt mortar with the best crack resistance performance is determined.ratio,laying the foundation for the application of asphalt elastic curing track bed materials in engineering.In this paper,based on the ratio of epoxy asphalt and high-rubber asphalt as curing track bed material determined earlier,the theoretical oil-stone ratio was determined based on the thickness of the asphalt film by the delta volume correction method.On the basis of the theoretical oil-stone ratio,the mixing ratio of four kinds of asphalt mortar mixed with rubber particles was determined by Marshall test,and the corresponding preparation and curing methods were proposed.According to the preparation and curing scheme of the corresponding asphalt mixture,four preparation and curing methods of asphalt mortar are proposed.First,the semicircular bending test was carried out to analyze the crack resistance performance of asphalt mortar at different temperatures.The fracture strength test results show that the fracture strength of epoxy-FAM is higher than that of rubber-FAM,and the fracture strength of different FAMs at low temperature is higher.The fracture energy results show that the ductility of 11%-epoxy-FAM is higher than that of 9%-epoxy-FAM,the ductility of 3%-rubber-FAM is higher than that of 6%-rubber-FAM,The crack ductility of rubber-FAM is better than that of epoxy-FAM,and it is more sensitive to temperature changes,and its fracture energy changes greatly.Secondly,the acoustic emission test based on the semicircular bending test and the low temperature splitting test was carried out,and the characteristic waveform changes during the cracking process were analyzed by the cluster analysis method.Acoustic emission test results show that the crack resistance of epoxy asphalt mortar is better than that of high rubber asphalt mortar,and the cracking is more stable.Among them,epoxy-FAM with 11% rubber content has the best crack resistance.Analysis combined with CT images showed that the incorporation of rubber particles did not affect the path of the main crack,but cracking was more likely to occur at the junction of rubber and asphalt.Based on the established discrete element particle flow model,the cracking mechanism of FAM specimens at different temperatures was studied.The crack analysis results show that the epoxy-FAM specimen has better temperature stability,and its number of cracks is less.The number of cracks simulated is correlated with the acoustic emission energy results.The influence of rubber particle content and particle size on the crack resistance of FAM was simulated and analyzed,and the recommended range of rubber particle content and particle size to maximize the crack resistance of FAM was given.The rubber particle content determined by the laboratory test is close to the recommended value determined by the virtual test,indicating that the actual rubber particle content is ideal.Based on the analysis results of laboratory test and virtual test,it is determined that epoxy-FAM with a rubber content of 11% has the best crack resistance.The results have good correlation.Therefore,it is an effective method to analyze the cracking performance of FAM through acoustic emission technology combined with discrete element simulation.. |
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