Influence of unsupported and partially supported sleepers on dynamic responses of train–track interaction

Abstract

One of the major problems of railroad deterioration is uneven settlement which occurs due to various reasons, including existence of defects in substructures, using non-homogenous ballast, or being poorly drained. Sometimes, because of these problems, sleepers remain freely as a part of vertical displacement and contact the ballast with load increase. Different models have been presented for checking the effect of hanging sleepers on the dynamic interaction of rail and train. In this paper, a mathematical model was developed for railway track and differential rail displacement with supported and unsupported sleepers was compared by modeling sleepers such as partially supported ones. On this basis, the motion equations of the train-track system were solved considering the non-linearity of wheel/rail contact form and using numerical integration in the time domain. Longitudinal sections of the track model were coded in Matlab software and the effect of one, two, or three partially supported sleepers and various spacing of sleepers on the sleepers and rail displacement was studied and compared with that of the unsupported one. It was shown that, with increasing the sleeper spacing from 50 to 75 cm, rail displacement increased from 7 to 22% in the unsupported sleeper and 5 to 8% in the partially supported sleeper. Additionally, rail displacement increased from 13 to 74% by changing the number of the unsupported sleeper from 1 to 9. Also, it increased from 6 to 24% in the partially supported sleepers.