The aim of this project is experimental monitoring, mathematical simulation and verification of railway subgrade structures applied in the Slovak railway tracks.
It is expected to realise experimental measurements and mathematical simulation at various border conditions from the point of view of soil formation design and of the applied conventional but also new materials to the railway subgrade.
These materials are differentiated by chosen physical – mechanical properties so it would be possible to take various thermo-technical properties and final thermal resistance into account.
The result of the project should be a methodology of design and assessment of railway subgrade from the point of view of unfavourable impact of frost also in relation to the changed climatic conditions, as a base for the prepared revision of the regulation S4 Railway substructure.
The optimisation of the technological procedures for the construction of subgrade structure for modernized, upgraded and rehabilitated railway sections by applying various methods and technology sets, taking into account the requirements of economic proposals for its implementation and maintenance.
Based on the experimental measurements made on models of railway construction at a scale of 1: 1, laboratory measurements (determination of specific thermal capacity and coefficients of thermal conductivity of selected materials used in the subgrade construction) and application of SVHEAT-SoilVision software for mathematical modelling of thermal regime of subgrade, there was a proposal to modify the existing method of dimensioning the underlay support for inadequate loading (effects of frost).
The proposal consists in changing the design values of the heat-technical parameters of the rolling bed material and the protective layer, as well as in the method of determining the design thickness of the protective layer. The significance of the new design nomogram is that the design of the design thickness of the protective layer takes into account not only the verified values of the heat-technical characteristics of the materials, but in addition to the frost index, another important climatic characteristic is also taken into account, namely the mean annual air temperature.
Following the use of the design nomogram, the important result is the knowledge that it is possible to omit the assessment of the underframe structure for an incompetent load in the case of areas where the design frost value Im, n ≤ 300 ° C or the average value. of average yearly temperature Tm ≥ 8 ° C.