Experimental study on fatigue properties and dynamic performances of new-type concrete-filled steel tube sleeper ballastless track

Abstract

The new-type concrete-filled steel tube (CFT) double-block sleeper ballastless track structure can better serve urban rail transit by overcoming the problems such as easy rusting and cracking of the traditional track structure. In this paper, a full-scale CFT sleeper ballastless track structure was manufactured by 11 new-type concrete-filled steel tube sleepers cast in place. A series of fatigue tests were carried out based on the CFT sleeper ballastless track, the distribution law and the variations of the strain and deformation on the ballastless track structure during the train fatigue loadings were obtained. The falling-shaft impact test was also conducted on the CFT sleeper ballastless track with Under Slab Mats (USM) before and after the fatigue tests, and the dynamic performance of the vibration-damping track structure were obtained. The following conclusions were obtained: The static response variations, namely the strain and deformation behaviors of the CFT sleeper ballastless track structure increase slightly under the fatigue loadings. There is no cracking phenomenon during the fatigue tests. The vertical self-vibration frequency of the CFT sleeper ballastless track with vibration-damping mat decreases by 9.26%. The vibration isolation effect of the vibration-damping track decreases from 15.37% to 13.76% during the fatigue tests, and the variations of VLzmax on the RC base, track bed and rail increase less than 7%. The findings of this research have a certain significance for promoting the engineering application of CFT sleeper ballastless track structure, and provide a reference for future research.