The paper characterizes the existing results and preliminary conclusions of mathematical modelling of the thermal regime of railway track structure carried out on the experimental stand and optimizes the structural thickness of the protective layer in the subgrade structure by the SVHEAT SoilVision software. SoilVision system is a modelling software based on the finite element method developed for geotechnical engineers. The first part describes the experimental stand design and methodology for monitoring the heat and humidity variations in the railway track structure [1]. This paper section characterizes the results of mathematical modelling of the thermal regime of the railway track model and subsequently carries out a comparison of results of experimental measurements and mathematical modelling by the SVHEAT [2]. The paper enables mathematical modelling of various combinations of material compositions of railway track structure after entering all the relevant input data of the winter periods. In this way, conditions for drawing up the relevant design nomograms for various types of subgrade structure or railway body types are created.
High quality of railway track construction is a major priority. One of the quality elements is the resistance to load of railway formation with individual structural layers caused by negative temperatures during the critical freezing period of winter. Numerical modelling allows obtaining more control outputs at different climatic loads. The presented paper shows the load of railway track model with different variants of climate and shows the importance in the designing of the non-transport load under negative temperatures, i.e. observation of transition of the zero isotherm through the layers of railway subgrade. If the subgrade layers of the railway formation are built with high quality and durability then the axis of the track will keep its geometric spatial position during the long-time operation.
Following the completed experimental monitoring of the temperature regime of the construction of a subgrade structure on the experimental stand of the Departments Railway Engineering and Track Management and measurement of thermal conductivity coefficients λ of building materials used in construction of a subgrade structure, there are constructed mathematical models, which are designed to not only verify the temperatures obtained in individual structural components of subgrade structure of experimental stand, but also the possibility to use appropriate software to model temperature regime of other types of constructions of subgrade structures. The paper presents mathematical models for the typical winter periods, which have been recorded since the beginning of the experimental measurements conducted from 2003 to the end of the winter period of 2013 using the software SV-HEAT SVOFFICE SoilVision [1] and there are also comparisons presented in achieving the position of zero isotherm in the construction of a subgrade structure. At the end of this paper, some of the knowledge obtained from the mathematical modelling of the temperature regime of the construction of a subgrade structure and confrontations with the temperature regime of a monitored, real railway track are underlined.
The design of railway lines under the current standard STN 73 6360 [1] including the comparison of railway line parameters to the European Standard EN 13803-1 and a new proposal in accordance to the new prepared standard STN 73 6360-1 [2] of Slovak Railways (ŽSR). Specifications of the basic design parameters of these standards: designing minimum radius values of horizontal and vertical alignment radii within these standards, for example at speeds: V = 160 km/h, V = 200 km/h and V = 250/300 km/h. The routes shown in the 3D model terrain surface. Dynamic spatial design of railway lines and their routing designs in 3D drawings, their development in the terrain and comparison according to the selected speed parameters.
Structural elements of railway buildings in transition zones are important parts of railway lines, where the structure of their materials is fundamentally changing. In the presented research results, these are changes in the railway body between a railway with a classic trackbed and a railway with a fixed track. The used materials of the transition zone and associated railway sections must be resistant to the effects of frost in winter. The experiments show the detected freezing depths using a zero isotherm at 0 °C. The temperature period before the onset of frost in winter is also an important factor. Numerical models of transition zones were loaded by freezing conditions. Based on the results of the experiments, frost protection measures have been proposed. To improve the temperature transition through the layers, materials with a low coefficient of thermal conductivity of transition zones have been proposed in the experimental models.
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