지하구조물 변위거동에 따른침목플로팅궤도의 고유진동수 분석 = Natural Frequency of Sleeper Floating Track System According to Displacement behavior of Underground Structures

다국어 초록 (Multilingual Abstract)

This study analyzes the influence of displacement behavior (uplift and subsidence) of underground structures, induced by adjacent excavation and variations in ground conditions, on the natural frequencies of sleeper floating track systems (STEDEF) installed within those structures. Modal testing was conducted on an operating line to measure the Frequency Response Function (FRF) of a sound track section, and a track geometry measurement system was used to measure vertical track irregularities in sections where structural displacement had occurred. Based on these results, a three-dimensional finite element analysis (FEA) model was constructed using solid elements from the rail to the concrete track slab. The model was validated by comparing the calculated natural frequencies with field measurements, after which the displacement behavior of the underground structure was applied as a boundary condition. The natural frequency analysis showed that, for the first mode, the natural frequency under general conditions was 9.68Hz and slightly increased to 9.88Hz under uplift conditions, whereas it decreased significantly to 4.10Hz under subsidence conditions. This reduction indicates a loss of track support stiffness and an increase in the effective span length between rail supports due to the occurrence of hanging sleepers. Therefore, natural frequency evaluation based on modal testing can be effectively utilized as a diagnostic technique for identifying track subsidence and hanging sleeper occurrence caused by deformation of underground structures.