Modeling of long-term train loads impacts on subgrade soils: a review

Subgrade is an important construction element of the railroad track. In the process of long-term operation, the subgrade is loaded by trains and exposed to natural climatic factors, such as wind and seismic loads, moisture caused by atmospheric precipitations and groundwater, exposure to positive and negative temperatures. At the same time, the subgrade must provide reliability and stable properties of the railway track because its renovations are the most expensive ones among those for the railway track in general. Due to this fact, national regulatory documents for the construction of the subgrade impose strict requirements on its deformity for the entire duration of modern railways operation. One of the ways to solve this problem on the stage of construction designing is computer predictive modelling of structural behavior that considers the changes of its elements and properties of construction materials under the long-term train impact taking into consideration the varying natural climatic factors. In this review, we analyze accumulated scientific and technical experience in formulating optimal approaches to the determination of initial data for computer simulation of repeated impact of the train loads for predicting railway track subgrade deformation considering engineering-geological conditions and natural climatic factors. We describe the stages of creating the subgrade computer modelling taking into account the analysis of trains load impact, the properties of model’s structural layers, and the change of soil properties under long-term loads.