The influence analysis of railway track support changes on its behavior under an applied load

Abstract

The main causes of inhomogeneity in the track foundation properties are primarily the contact loss between the track and the sleeper with the ballast, the non-uniformity deformability of the granular layers and the local deformation of the railway ballast foundation. These inhomogeneities, like geometric irregularities, significantly impact the railway track operation (e.g. progressive track structure degradation or increased dynamic load). The problem of the support changes on the behavior of the rail and sleeper during the operation of a jointless railway track were analyzed in the paper. The author proposed a method for simulating a gap in the railway track (contact loss between the sleeper and ballast). The proposed method, based on the measurement in the loaded track (a static load from the locomotive wheels), allows for a description of the effect of the changing track support condition. Using the results of the author’s test and the investigations described in the literature, one can propose the parameters of foundation for theoretical calculations of rail deflection during the railway track support changes. In the paper, the influence of the changing track support condition was presented in figures, which clearly show the changes in deflections and bending moments. Change of the contact loss between the track and the foundation from only along one sleeper spacing to along two sleepers spacing causes a twofold increase in rail deflection and stress for the concentrated forces analyzed in the paper. During the track operation, a lack of support along the length of the railway sleeper also occurs. The analysis showed, that lack of support in the under-rail section with an increase in the sleeper support factor (in the middle section) results in a large increase in deflection, especially for wooden sleeper. The nov - elty introduced by the author’s analyses is generating the lack of support between the track and ballast in a known place in the track, identification of foundation parameters, their application in beam-on-elastic foundation models and the analysis of schemes of contact loss between the jointless track and foundation. The author’s contribution to this problem lies in preparing a track analysis based on the numerical calculations of the analyzed models.