Experimental and numerical investigation of usp for optimization of transition zone of railway

Abstract

To meet the increasing demands and be competitive in the market, railway systems must be sustainable. One of the important criteria for sustainability is to have lower life cycle costs (LCC). Several statistics report higher track geometry degradation in transition zones, and maintenance of these zones has a large share in LCC. One of the reasons behind the accelerated track degradation is the wear and the breakage of ballast in transition zones due to sudden stiffness changes and ballast vibrations. Optimized track support solutions can have a positive impact on track degradation in transition zones. Under sleeper pads (USP) as supporting elastic elements are being used to decrease stress and vibration on the ballast. In this study, numerical models with and without USP components are built for the selected transition zone. Numerical models simulate dynamic load from train passages and impact hammer load. Thus, the USP component effect on vibrational behavior of the track is analyzed. For the validation of simulations, several experiments were carried out on the selected transition zone. In addition to them, vibration mitigation experiments were performed. According to the simulation and experimental outcomes of the study, the developed models are satisfactorily in compliance with experimental results. It has been observed from simulation results that the integration of the USP component into track provides an approximately 25% decrease in ballast acceleration. On the other hand, it has a negative effect on rail and sleepers by increasing their vibration. Since this is an expected outcome of USP, the methodology in the study can be beneficial in the design phase.