Modeling Shakedown Plastic Strains of Subballast and Subgrade Materials in the Concrete Slab Track System of High-Speed Trains

초록

Recently, the Korean government is driving a research and development project for a high-speed railway system which is capable of operating in the maximum speed over 400km/h. Besides the vehicle system, the track and railroad system should also be built properly to cope with the sustainable operation of the high-speed trains. The concrete slab track system is being introduced to reduce the cost of frequent maintenance in the conventional ballast track. This introduction also demands a new geotechnical assessment on the performance of the subsoil materials. It is of interest that we should estimate and control cumulative plastic strains in total operation period. The stress distribution in the subsoil materials beneath the concrete slab track becomes more sophisticated than the ballistic track system. The shakedown phenomena, in which the permanent deformation rate at a number of load cycles has become negligible small and the cyclic response has become elastic, should be understood for better design of railway track. This study, described in this paper, investigated the pattern of the development of the shakedown plastic strains of the subsoil materials subjected to dynamic loads induced by high-speed trains on the stiff concrete slab track system. A constitutive model that captures only the envelope of the maximum plastic deformations generated during the cyclic loading process was employed. The accumulated plastic displacement measured in a series of full-scale model tests was compared with the predicted results using the proposed model