Simple plastic deformation analysis of ballasted track under repeated moving-wheel loads by cumulative damage model

Abstract

This study examines a simplified and practical prediction method for the cumulative residual settlement of ballasted track under repeated train passages, and the applicability and usefulness of the proposed method are discussed by comparing the experimental results of cyclic loading tests of model ballasted track structures with the analytical results. As the results, this study proposed a new analytical procedure with iterative calculation by linear elastic Finite Element (FE) analysis, which can evaluate the effects of continuous rotation of principal stress axis due to moving-wheel loads by taking into consideration the cumulative strain characteristics of ballast obtained from laboratory element tests such as multi-ring shear tests adopting the moving-wheel loading method in terms of the practical use. In addition, it was revealed that when laboratory element tests with high accuracy was conducted under experimental conditions similar to the actual phenomena in order to grasp the cumulative strain characteristics of ballast and then plastic deformation analysis was performed based on the findings above, the proposed analytical procedure could roughly estimate the cyclic plastic deformation of railroad ballast under repeated moving-wheel loads even with a simple linear elastic FE analysis. These findings confirm sufficient applicability of the proposed analytical procedure to the estimation of the cumulative residual settlement observed at ballasted track structures subjected to repeated train passages.