Search results

The article focuses on the consideration of the issue of ensuring the safety of fine coals transported on open-top rolling stock in the matter of minimizing their losses due to blow-out. An aerodynamic model of the coal blow-out process during its transportation by open-top cars was created and studied in specialized software in the field of fluid dynamics research (CFD), which provided an opportunity to numerically estimate the size of coal losses from blow-out using data on the aerodynamic parameters of air flows flowing around the cargo surface. The study of the influence of train speed on the size of losses of fine coals from blowing was carried out by modeling the blowing process with varying train speeds from 20 to 140 km/h, which also allowed us to establish the speed of the beginning of the intensive blowing-out of small cargo particles - 40 km/h. This speed value is consistent with that obtained by scientists from the Siberian Transport University during mass experimental transportation of bulk cargo in the 60-70s of the last century, which indicates the adequacy of the results obtained during the modeling of the blowing process. The results of the study made it possible to estimate numerical dependences of the size of losses of coal fine particles due to blow-out from changes in train speed, which is important to consider when choosing coal-dust mitigation measures to reduce the size of losses from blow-out. Further refinement of the obtained dependencies for other fine-grained bulk cargo seems possible using the developed aerodynamic model of the blowing process, both by specifying the value of the critical blowing speed of an individual bulk cargo, and also due to the formation of the corresponding shape of the cargo surface, characteristic of a certain loading method and the parameters of the open-top car model, which affect the loading height, is an equally important factor determining the size of losses from blowing.

The subject of the research is a sub-rail foundation containing a viscous element. The purpose of the study is to evaluate the effect of including a viscous element in the elastic system (rails, sleepers, ballast, etc.) on the overall rigidity of a railway track. The design of a sub-rail foundation with a viscous element is described by the generalized Maxwell model and contains a shell filled with a Newtonian fluid, in particular air. Pneumatic shells with different thicknesses were considered. The modeling was carried out in the finite element analysis environment. Mathematical models of a track section with a sub-rail device containing a pneumatic shell were constructed. The calculation results showed the absence of a sharp increase in internal force factors and stress concentration in typical track sections when laying a sub-rail foundation with a pneumatic element. A change in the overall rigidity in the vertical plane did not lead to a significant change in bending stresses in the edges of the rails. With a small shell thickness, the bending stresses in the upper area of the sleeper decrease to 35 %, and in the lower area by 15 %. The maximum increase of up to 8 % is observed with a sharp difference in the shell thicknesses. Compressive stresses on the sleeper in the under-rail zone increase with a small shell thickness of the device due to the redistribution of forces to a smaller number of under-rail supports when the overall rigidity of the structure changes. Increasing the shell thickness to 40 cm leads to an increase in mechanical stresses of up to 20 %, which is an acceptable value with a large margin. The use of under-rail foundations with a viscous element is recommended for temporary railway tracks when laying them instead of ballast and sleepers, which allows for the track to be quickly laid and also quickly dismantled.

The use of three-dimensional reinforcing structures is an effective method strengthen the slopes and the primary site of subgrade, it is confirmed by a complex of experimental studies. The numerical and natural modeling processes associated with the strengthening of subgrade geokompozitn structure. Natural modeling performed by the embankment of equivalent materials using real ground conditions and loadings identical in size natural. A comparison of simulation results showed high convergence, which allows use it’s in the preparation of design techniques.