Abstract
The piston effect of trains on air distribution and air exchange in tunnel and passenger structures of the metro with a single-track tunnel is in second place after the action of mechanical tunnel ventilation. When the tunnel fans are turned off (for example, during the cold season in an area with a sharply continental climate), almost the entire ventilation load is provided by the piston action. Since all elements of the metro ventilation network are connected by tunnels under the generally accepted scheme of longitudinal ventilation, the mutual influence of the ventilation modes of neighboring metro sections is very significant. Therefore, in order to obtain the correct result of air distribution modeling, at least 8 runs with stations should be included in the calculation scheme, which leads to increased requirements for computing power and calculation time. The article considers the decomposition of an extended metro line using ring models and justifies the number of calculated sections with stations for different train frequencies. A comparison of the calculation results for the ring and linear models is given. Calculations are performed using network methods for calculating air distribution.