FEM analysis of the effects of the ballast renewal work on continuous welded rails and proposal of the new restriction of work at a low temperature

Abstract

This study aims to establish a new restriction of ballast renewal works at a low temperature in winter. The authors construct a FEM model of railway track which simulates the ballast renewal work at a low temperature and perform the FEM analysis under the various conditions of track radius of curvatures R, length of ballast renewal work L and decrease in rail temperatures Δt. As a results, it becomes clear that the inward rail displacements and changes in axial rail forces increased with the decrease in R, and the increase in L and Δt. Based on FEM results, the authors propose the restriction diagrams of ballast renewal work which provide the allowable decrease in rail temperatures from the neutral temperatures of rail newly welded under the restriction of converted temperature of changes in rail forces, inward rail displacements and alignment defects due to inward displacements. Furthermore the authors propose the flow for users to judge propriety of ballast renewal work at a low temperature by use of the restriction diagrams. Consequently, the ballast renewal work at a low temperatures exceeding the current restriction can be executed.