Homogenizing Track Stiffness of a Mixed Railway Line Turnout Crossing Using Rail Pads and Under Sleeper Pad
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Date
2021-01
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Addis Ababa University
Abstract
Turnout is among the weakest parts in railway with disadvantages of complexity, short working life, limited speed, low driving safety and high maintenance and operation costs compared to the tangent tracks. These could be due to the fact that turnouts contain several irregularities both in stiffness and inertia. Thus, these variations of mass distribution and geometric irregularities lead to stiffness variation along the turnout. Furthermore, the existence of shared baseplates and spacer blocks between different rails makes the variation severe at the crossing.
This research work investigates the stiffness characteristics along a selected railway turnout crossing from Awash-Kombolcha-Hara Gebaya mixed railway line and proposes suitable rail pads and under sleeper pads to improve abrupt stiffness fluctuations throughout.
A 3D numerical model is established using ABAQUS 6.19 to do deterministic analysis on the characteristics of stiffness along the selected turnout. The FEA model consists a rolling wheel, a through root in a right branching turnout, rail pads, sleepers, under sleeper pads, and ballast and it was first verified by using a static analysis comparison with previously validated simulation model.
The parameters used in the model are extracted from Ethiopian Railway Corporation design files; In the case of data which is not stated there, well recognized literatures are referred. The analysis results for the initial parameters (the as built) shows stiffness increment of about 54 % and reduction of 23% at the approach and crossing panels compared to the crossing nose. The homogenization results a maximum of 19 % stiffness variation between consecutive points altering the stiffness of rail pads and under sleeper pads together. It is also recommended to incorporate other design optimization outputs including rail shape and sleeper spacings in addition to decreasing the density of the ballast under the crossing panel to get the maximum out of this research.
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Keywords
Turnout, Vertical stiffness, Stiffness variation, Geometric irregularities, Deterministic analysis, Rail pads, USPs