노반의 강성 변화가 궤도수직강성에 미치는 영향 및 경제성 분석

초록

Vertical stiffness of track of high speed railway with ballasted track provides two contrasting characteristics. With high vertical stiffness, deterioration of the geometry of the track is accelerated. So the cost of maintaining the geometric quality of a track increases. Though dynamic loads decrease with excessively flexible track, however, more energy is dissipated by the vehicle, which leads to higher operating costs. Therefore, there is an optimum vertical stiffness of the track that provides a compromise between the contrasting effects. In this study, numerical analysis was performed to analyze the effect of stiffness variation of subgrade on vertical stiffness of track, and to derive the optimum stiffness of subgrade. 3 types of subgrades(soil, crushed aggregate, concrete) were used, and the stiffness of subgrade were divided to upper, upper-intermediate, intermediate, lower-intermediate, and lower stiffness levels. From the results, optimal vertical stiffness of the track (63.0~77.2 MN/m) was obtained in soil and crushed aggregated subgrade with the stiffness higher than upper-intermediate stiffness. However, it was found that all subgrades with concrete type showed uneconomical range of vertical stiffness(more than 106 MN/m), so it was concluded that railpads with lower stiffness to decrease a vertical stiffness of track should be installed.