Вероятностно-детерминированный подход к расчету пожарного риска, вызванного воздействием лучистого теплового потока от фронта верхового устойчивого повального лесного пожара на жилой дом

Abstract

Purpose. The purpose of the article is to create a mathematical model for calculating the fire risk caused by the impact of a radiant heat flux from the front of an independent crown wild fire on the combustible structures of a residential building. A combined calculation method has been developed that combines deterministic and probabilistic approaches. The combination of the above mentioned approaches is due to the fact that the probabilistic approach does not take into account the specific mechanism of the impact of a wild fire on the structure of a building, while the deterministic approach does not take into consideration the probability of a fire starting ABSTRACT and developing, as well as the timeliness of fire units response for fire extinguishing. Methods. The study uses theoretical methods of heat conduction and radiant heat transfer, wild fire statistics analysis, and fire risk theory. Findings. In the deterministic part of the method to calculate the temperature of the irradiated surface of the building structure, a one-dimensional non-stationary heat conduction equation is used, the boundary condition for which is determined by solving the equation of the radiant heat transfer between the wild fire front and the building. The calculated wood (pine) ignition time is compared with experimental data. The agreement between the calculation and experiment is satisfactory. The formula for calculating the fire risk for a residential building resulted from the impact of the radiant heat flux from the front of a wild fire is proposed. The above-mentioned formula takes into account the frequency of crown wild fires occurrence, the probability of ignition of combustible structures of the building when no firefighting measures are taken, as well as the probability of the active and passive fire prevention measures effectiveness. An example of fire risk calculation is presented when constructing a mineralized line, whose increase in width will reduce the fire risk by 1 000 times. Research application field. The results of the study can be applied in the development of fire prevention measures aimed at protecting communities against wild fires impact. Conclusions. The developed probabilistic-deterministic mathematical model for calculating the impact of a radiant heat flux falling from the front of an independent crown wild fire on the combustible structures of a residential building makes it possible to assess the fire risk for a building, considering specific meteorological conditions, pyrological and geometric (tree height, etc.) characteristics of the woodland, the distance from the building to the edge of the forest, as well as fire prevention measures implementation.