Calculations using the example of a reinforced concrete ribbed slab have shown that if, as a result of an explosion, due to cracks that have arisen, a part of the compressed concrete layer is turned off, then even while maintaining the bearing capacity of the slab, its fire resistance is significantly reduced. It is shown that on the basis of the proposed methodology for studying the behavior of bending elements under the combined effect of "explosion-fire", it is possible to take into account the necessary parameters of reinforced concrete ribbed slabs in the design and operation of structures of hazardous operations industrial facilities. Also, the proposed technique makes it possible to predict a relatively safe amount of explosive in the technological process of an hazardous operations industrial facility, without leading to catastrophic consequences.

Purpose of work. Determination of the terms of weakening the destructive action of a shock wave during its propagation in the channels of mining workings or long communication premises of industrial buildings in an emergency explosion. Methods. Using an analytical research method based on the main provisions of theory of combustion and explosion. Construction and analysis of the physical model of formation and distribution of a shock wave in the channel. Results. The problem of weakening of a shock wave during its propagation in long channels of mining workings or communication passageways of industrial buildings with a potentially explosive atmosphere is considered. It is shown that when an explosion in the channel is formed by a head shock wave with a flat front, dynamic pressure which significantly exceeds the pressure on the fronts of falling and reflected shock waves that form the head shock wave. A physical model of formation and distribution of a shock wave in a channel with walls of different rigidity is proposed. It is shown that if one of the walls of the channel is mobile or easily deformed, it leads to a violation of the geometry of the plane front of the head shock wave and its weakening. Moreover, the reconstruction of the plane front of the head shock wave can occur at a distance of not less than 6-8 channel width. On the basis of this observation, the need to arrange explosion-relief valves in channels of mining workings or communication premises of industrial buildings with a potentially explosive atmosphere is substantiated. Novelty. A physical model of the formation and propagation of a shock wave in a channel with walls of different stiffness is proposed. The necessity of equipping explosion-relief valves in the long communication channels of mine workings and buildings with increased explosion hazard to attenuate the shock wave is substantiated. Practical significance. Arrangement of expanders with explosion-relief valves with dimensions comparable to the channel diameter and intervals between them up to 8 channel diameters in long communication channels of mine workings and buildings with increased explosion hazard will lead to weakening of the shock wave and reduction of its destructive effect.