재하방식에 따른 자갈궤도 종방향 저항 특성 및 항복강도 산정

초록

To investigate the longitudinal resistance behavior of ballasted tracks on railway bridges, a full-scale specimen with five UIC 60 kg sleepers was fabricated, and rail-end loading and slab-end loading tests were conducted under both unloaded and vertically loaded conditions. In the rail-end loading tests, the axial elastic elongation of the rail itself was included in the measured displacement; thus, the apparent initial stiffness was higher than that specified in the design code, and a larger displacement was required for full plastic mobilization owing to sequential load transfer among sleepers. In contrast, the slab-end loading tests simultaneously imposed identical slip on all sleepers, directly reflecting the local resistance–slip relationship of the ballast. Both test methods exhibited nonlinear behavior, in which the resistance increased gradually and continuously after yielding, in contrast with the bilinear model assumed in current design codes. The small-displacement slab-end loading data were fitted to the Ramberg–Osgood model, reproducing the experimental curves with a coefficient of determination (R²) exceeding 0.998 and a well-defined yield point. The data can be utilized in a nonlinear resistance model to improve the accuracy of track-bridge interaction analysis.

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