| China's high-speed railway development has made great achievement,by the end of 2016,the total operating mileage will exceed 23,600 kilometers,which also exceed all foreign high-speed railway mileages.How to ensure the long-term operation of such large-scale high-speed railway safe and stable is the key and difficult point of high-speed railway engineering research in China.It's facing the challenge.As China's high-speed railway service environment is complex and varied,with the lack of maintenance experiences,ballastless track layers deterioration and damage,such as slab interface crack?self-compacting concrete filling layer damage occur occasionally.Therefore,revealing the influence of interface crack on the dynamic performance of ballastless track structure is of great theoretical and engineering application value for the operation and maintenance of ballastless track in high speed railway.In this paper,based on interface crack for CRTS III ballastless track,the influence of one-sided crack on the dynamic characteristics of the track-subgrade under the impact load and the vehicle load is analyzed.The main contents and conclusions are as follows:Base on the full-scale model of CRTS III ballastless track-subgrade system,the distribution characteristics of the interface crack between the slab and the self-compacting concrete filling layer were measured and counted,with CRTS III ballastless track-subgrade drop-wheelset experiment conducted.The dynamic response of distribution regularities for track-subgrade structure under impact load is counted and analyzed,the three-dimensional dynamical analysis model of overall CRTS III track-subgrade with a one-sided crack was established based on the software ANSYS/Ls-Dyna,which analyzed the influence of one-sided crack on infrastructures dynamic characteristics.In addition,the results were made comparisons with experiment data.The results show that the ballastless track has great damping capacity and diffusion load capacity,the load is greatly attenuated during the transmission from the rail and fastener system to the track-subgrade structure.Under the impact load,the vibration response amplitude decrease along track longitudinal and vertical as vibration transmission distance increase.The distribution trend of slab of different crack widths vertical dynamic stress along horizontal is basically the same,showing the trend of hump distribution,and the dynamic response amplitude of the crack side is larger than that of the non-crack side.When one-sided crack within range of 0-800mm,basic infrastructures displacement increase as the crack width increase,slab displacement increase maximally,rail,slab and subgrade vertical acceleration increase as crack width increase,slab displacement increase maximally;when the slab doesn't extend to the bottom of rail,self-contacting layer,supporting layer and subgrade surface vertical acceleration decrease as the slab width increase.The influence of the height of one-sided crack on the displacement and acceleration is small.The closer the layer to the crack is,the more obvious the dynamic characteristics are affected.When the crack height is at the range of 0-3mm,the displacement and vertical acceleration of infrastructures increase slightly with the increase of the crack height,with the maximum increase is no more than 13%.Under load vehicle,the CRTS III slab track crack will cause track-subgrade structure vibration response abnormal changes,and bring about greater impact to dynamic response of the wheel-rail vertical force,wheel unloading rate and the structure of the track subgrade.The dynamic response of each structure is larger than that of the non-crack side.The dynamic response of the track-subgrade structure increases with the height and length of the crack,and the vibration in the central place of slab is greater than the side of slab.Self-contacting layer,supporting layer and subgrade surface vibration acceleration and dynamic stress reach the maximum value when crack width is in the vicinity of the rail bottom,then both values decrease an the crack width increase..The structure with the largest variation of dynamic response usually appears in the vicinity of the crack,that is the slab and the self-compacting layer,which have little effect on the rail and the subgrade.The closer to crack,the influence affected by crack on the track-subgrade structure is greater. |
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