Problems of designing fire protection systems for subways

Abstract

В статье рассмотрены проблемы проектирования систем обеспечения противопожарной защиты метрополитенов. Отмечено, что вопросам обеспечения пожарной безопасности на объектах метрополитенов уделяется особое внимание со стороны как контрольно-надзорных органов, так и специалистов, участвующих в разработке нормативных документов. При недостаточном уровне защиты от пожара нахождение в метрополитене чрезвычайно опасно, поскольку существует удаленность от поверхности и возможность быстрого задымления, что может привести к массовой гибели людей и значительным социально-экономическим последствиям. Предложены пути решения проблем, связанных с обеспечением пожарной безопасности метрополитенов. The article deals with the problematic issues of designing systems for ensuring fire protection of subways. To date, there is no precise definition of the functional fire hazard class for a metro station in regulatory documents. An object with a massive stay of people, primarily in terms of evacuation of people in case of fire, is considered one of the most difficult. Based on this fact alone, when designing a metro line and stations, special technical conditions are necessarily developed. The existing set of rules for subways is not included in the list of regulatory documents that ensure compliance with fire safety requirements. Many questions arise when designing smoke ventilation systems, since the provisions of the existing set of rules, as one of the main regulatory documents for the design of smoke protection systems, cannot be fully applied to underground metro structures. The parameters and modes of air exchange in an extensive metro network depend not only on the selected operating modes of ventilation equipment, but also on the piston effect from the movement of trains in tunnels, on the configuration of buildings and wind load in the area of ventilation shafts on the surface, season, etc. A separate important issue is ensuring the stability of the air flow in case of fire. In practice, the phenomenon of “overturning the jet” is known – a change in direction, a reversal of the movement of the air flow in the mine due to a change in pressure in the area with a fire. According to the set of rules, the stability of the air flow is ensured if the calculated speed of the air flow in the area exceeds the critical speed. The critical speed in this case depends only on the section of the tunnel and the slope. Neither the design power of the fire, nor other significant parameters are taken into account when determining it, which, of course, is not entirely correct from a physical point of view. The ways of solving problematic issues related to ensuring the fire safety of subways are proposed.