Analysis of discrete - continuous model of vibroisolation system of railway substructure

Based on analysis of the railroads, construction can be concluded that the wide variety of design of the track rail vehicles is applicable in the country. The constructions of railways tracks can be divided into two main groups: separate trackways and built-in trackways. In the paper, a construction of vibroisolated trackway built-in or located on engineering structure such as bridge or viaduct is presented. This proposed construction of trackway consists of an embankment of land on which the bottom slab is located. On the concrete bottom slab, the perforated rubber plates are stacked constituting the elastic vibration isolation system. On the rubber platen, the concrete slab constituting the so-called inertial mass is mounted. Then, on the platen, the sand bed and the two layers of gravel with a variable grain size are placed. The final layer of crushed stone reaches the level of railway ties to which the elastic rail pads are attached. The several mathematical models of such vibration isolation systems of railway tracks were proposed. One of these models allowing for an analysis that allows to formulate both optimum conditions due to the selection and distribution of elastic-damping elements to ensure the translational movement of the platen and the vehicle so the vibration isolation system was “highly tuned”, i.e. the natural frequency of the system was higher than the frequency of excitation caused by rail vehicles. It is a new trend in the design and selection of vibration isolation systems of railway tracks. In the paper, the conception of discrete-continuous vibration isolation system in which a continuous part is the beam supported on discretely distributed elastic elements is presented. The load to the system is modelling as solid body simulating the moving rail vehicle. The results of this analysis are the main part of the proper selection of vibration isolation system of railway tracks.