Study On Fire Extinguishing Mechanism And Influencing Factors Of Explosion In Soil

Forest fire prevention and control is recognized as a worldwide problem.Limited by the geographical location and environment of the fire site,the fire fighting effect of traditional rescue and fire fighting methods is often poor.There are better conditions for the occurrence of soil in the forest fire environment,so the compound action of high-speed impact airflow produced by explosive explosion in soil and throwing soil is studied to extinguish the initial fire source of forest.Firstly,the action mechanism and influence conditions of explosion covering soil are analyzed theoretically,and then the explosion impact velocity,soil throwing range and soil covering fire extinguishing effect are numerically simulated by simulation software.Finally,a series of field soil particle tests and fire extinguishing tests were carried out,and the effects of charge quantity and burying depth on the fire extinguishing effect of explosive covering soil were analyzed.The main research contents and conclusions are as follows:The main research contents and conclusions are as follows:(1)the explosive spraying effect of different types of soil is different,and the explosive spraying effect of non-cohesive soil is better than that of clayey soil.With the increase of the amount of explosive,the range of explosive cover increases at first and then slows down,but with the increase of burial depth,the range of explosive cover increases and then decreases.The lower soil of the explosive is compacted by the explosion,and the explosive energy mostly acts on the soil,which leads to the weak throwing effect,the bulging of the upper soil is easy to form,and the increasing rate of pit depth decreases gradually after reaching the peak value.(2)it is studied that the high-speed airflow generated by the detonation source is affected by the buried depth and the amount of charge.The numerical simulation results of high-speed airflow after explosion under five different working conditions show that the higher the amount of charge in the pit is,the faster the gas diffusion is,the shallower the depth of the pit is,the easier the shock wave of explosion is;when the buried depth is too high,the energy acts on the upper part and the surrounding soil after the explosion of the buried deep explosive,which results in the limitation of the air diffusion after explosion,and the diffusion effect of the charge height lower than the buried depth is better than that of the charge with the same charge quantity on the ground.(3)using Pyrosim simulation software to set up four parameter fire extinguishing models with different fire source size,injection orientation,soil properties and spray flow rate,and carry on the numerical simulation study of soil particle fire extinguishing,the fire extinguishing effect of soil particles is more than 80%;the fire extinguishing degree of spray orientation is greater than soil properties and spray flow rate,and the actual fire fighting should focus on the burying position of explosives:the influence of charge quantity on fire extinguishing effect is obvious,and the influence degree can reach 10%.The soil properties have a great influence on the fire extinguishing effect,so it is suggested that explosive covering soil should be given priority to extinguish the fire in the dry soil environment.The fire extinguishing effect of soil particles is closely related to the size of the initial fire source,and the small fire source can be completely extinguished by the ejected soil particles.The fire sites with the radius of 3 meters and 2 meters in the field test can be extinguished by explosion overpressure and soil covering,and the fire extinguishing effect is obvious.