Study On Effect Of Slab Track Structure Defect On Dynamic Performance

Following the rapid development of High-Speed Railway and Urban railway system, ballastless track is widely used with the advantage of highly stability, less maintenance,etc. However, due to production technology, construction technology and other conditions, the ballastless track will inevitably lead to fastener failure, differential settlement in subgrade, stepped irregularities of slab,welded rail joint irregularities, cement asphalt mortar cataclasm and other diseases in track structure, which affects the service life of the structure, driving safety and riding quality of high-speed train. Thus,to discover the effects of slab track structure defect on dynamic performance is significant in theory and engineering application.In this paper, slab track is set as the research object. Based on the vehicle-track vertical coupling dynamics theory, a finite element model of Vehicle-Slab track is established by ANSYS and APDL. The effect of slab track structure defect on dynamic performance is studied according to this model.The fastener failure results demonstrate that the effect of wheel-rail dynamics sharply rise when vehicle pass through the section of fastener failure; the more failed fasteners are, the intenser the effect of wheel-rail dynamics is; with the speed increase, the stronger effect of failed fastener on dynamic performance of slab track is.The results of differential settlement in subgrade. show that differential settlement in subgrade is mainly impact the vibration acceleration of slab and cement asphalt mortar destruction;with the increase of speed, the destructive effects of differential settlement in subgrade on the track structure and track parts is increasing; settlement of magnitude more Large, the larger the magnitude of settlement is the more fierce the vibration of the track is.After study of the stepped irregularity of slab track, the result shows that stepped irregularity of slab track has a huge effect on dynamic performance of slab track, so strictly control should be done; with the increase of the train speed and the amplitude of stepped irregularity,the wheel-rail dynamic effect rise sharply; the shortening of the extent of rail deformation will lead to a significant increase of wheel-rail impact.The results of welded rail joint irregularities display that welded rail joint irregularities mainly affact wheel-rail impact; following the increase of amplitude of irregularities, dynamic effect between wheel and rail dramatically enhancement.The results of the study on the effect of voided slab induced by deteriorations of cement asphalt mortar layer demonstrate that deteriorations of cement asphalt mortar layer has a great impact on track structure, mainly in the enhancement of vibration acceleration of track; the area of deterioration will be rapidly expanded and the service life of cement asphalt mortar layer will be greatly shorten if the deteriorated cement asphalt mortar layer isn't repaired in time.