Investigation of rail irregularity effects on wheel/rail dynamic force in slab track: Comparison of two and three dimensional models

Rail irregularity is one of the most significant load amplification factors in railway track systems. In this paper, the capability and effectiveness of the two main railway slab tracks modeling techniques in prediction of the influences of rail irregularities on the Wheel/Rail Dynamic Force (WRDF) were investigated. For this purpose, two 2D and 3D numerical models of vehicle/discontinuous slab track interaction were developed. The validation of the numerical models was made by comparing the results of the models with those obtained from comprehensive field tests carried out in this research. The effects of the harmonic and non-harmonic rail irregularities on the WRDF obtained from 3D and 2D models were investigated. The results indicate that the difference between WRDF obtained from 2D and 3D models is negligible when the irregularities on the right and left rails are the same. However, as the difference between irregularities of the right and left rails increases, the results obtained from 2D and 3D models are considerably different. The results indicate that 2D models have limitations in prediction of WRDF; that is, a 3D modeling technique is required to predict WRDF when there is uneven or non-harmonic irregularity with large amplitudes. The size and extent of the influences of rail irregularities on the wheel/rail forces were discussed leading to provide a better understanding of the rail-wheel contact behavior and the required techniques for predicting WRDF.