Theoretical Modelling And In-situ Test Of Metro Train-Steel Spring Floating Slab Track Interaction System

With the development of urban railway system, the environmental vibration caused by metro operation becomes more and more important. The different types of track systems have great influence on subway vibration, in which the steel spring floating slab track structure is known as the best track structure to reduce the vibration and noise effect This paper has focused on the theoretical modeling and in-situ testing of metro train-steel spring floating slab track coupling interaction.The existing work usually use the beam model or plate model for the dynamic analysis of floating slabs, As well known, the Timoshenko beam model is based on the one dimensional theory and can not consider the effect of the beam width, while the two-dimensional plate theory need very complicated calculations. In the paper we introduce the Mindlin plate-beam theory, which is deduced from the Mindlin plate theory and can consider into it the influence of beam width. The vibration characteristics of a wide beam with or without the Winkler foundation have been investigated here through numerical examples. It can be concluded that the Mindlin plate-beam theory is especially suitable for dynamic analysis of the wide beam structure (or structure of narrow slabs).Second, use the Mindlin plate-beam theory for the modelling of the floating slab, and establish the metro train-floating slab track interaction system. The dynamic equation of the system model is derived. Here, wheel-rail contact is assumed to be linear and elastic, while the subway sleepers and steel springs of the floating slabs are simulated by discrete spring dampers. The modal superposition method is employed and the system equation is transformed into a series of coupling ordinary differential equations. Based on the method of Newmark integration, the dynamic responses of train-track system are finally obtained. The effects of parameters, such as the length and the spring stiffness of the floating slab, the vehicle speed, on the dynamic responses of the system are also analyzed. Finally, an in-situ test is performed based on a steel spring floating slab track at Hangzhou. The accelerations of rail and the floating slabs are measured. Through the analysis of the data, the vibration acceleration magnitudes, frequency distribution and Z vibration level of rail and the floating slab are calculated. This test prove that the floating slab track have an excellent vibration isolation performance.