Study of the interaction forces between rails and sleepers in case of uneven track settlement

The study examines the effect of uneven track settlement on the force interaction between rails and sleepers when affecting the track of a freight train. Due to the presence of gaps between the elements of the track superstructure, the difference in the mechanical characteristics of the elastic gaskets and the soil base in the longitudinal direction, the settlement of the sleepers may be uneven. The importance of this factor increases with increasing axial loads and load stress. In the end, individual sleepers have a greater load than others compared to the calculated normative state of the track.

The analytical solution to the problem of determining the interaction forces between rails and sleepers under uneven settlement proves to be difficult and cumbersome. In this work, the numerical modeling method was used – the finite element method. For the rail, a mathematical model of the beam was used, resting on an elastic base, the pressure on which linearly depends on the movements of the rail, and its rigidity on a combination of deformation characteristics of rail and napkin rubber pads and soil. Based on this model, a finite element scheme for calculating rails supported by sleepers under the influence of a standard load was built. Track settlement was modeled by changing the parameters of special contact finite elements. When varying the parameters of these elements, the maximum rail pressure on a single sleeper was calculated. From the analysis of the results, the most unfavorable cases of base settlement unevenness were identified. It was found that the settlement of the track, in which one sleeper is turned off from the operation of the topsides, leads to an increase in maximum pressure by 25%. The shutdown of four adjacent sleepers increases the maximum pressure by 2.16 times compared to the standard condition of the railway track. This circumstance should be taken into account when calculating the strength of railway ties.

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