Simulation Study On Fire Flashover And Group Fire Spread Of Wooden Stilted Buildings

The wooden structures left in the long river have high cultural value and provide theoretical support for the prevention and control of fires in wooden structure buildings.This paper uses literature collection and field investigation as data support,and uses mathematical methods and numerical simulation methods to study The fire flashover and the spread of group fires in the stilt-foot building are finally used for actual verification and analysis of the fire hazard of the wood structure building group.For the first time,the catastrophe theory was introduced into the prediction study of fire flashover in the confined space of wood structure buildings and the critical value of fire spread of adjacent wood structure buildings,and was verified by numerical simulation,and the critical value of fire spread of adjacent wood structure buildings was also added to the study.Simple experiments are carried out to support the results.Finally,it is considered that the fire flashover in the confined space of the wood structure building belongs to the dovetail catastrophe.The dovetail catastrophe theory predicts that the critical temperature of fire flashover is 951.5 K,and the numerical simulation results calculate the critical temperature to be 953.4 K and 955.7 K;the fire spreads from the burned building to The process of unburned building belongs to the cusp catastrophe.The cusp catastrophe theory predicts the critical temperature to be 892.2 K,and the numerical simulation predicts the critical temperature to be 881.5 K.The simple experimental results are close to these two values.The results also demonstrate the effectiveness of mutation theory in the prediction of fire threshold in wooden stilted buildings.Secondly,analyze the fire situation in three different relative positions of the wood structure building,obtain the change curve of CO concentration,visibility and temperature at different positions in the ignited wood structure building,and find the overlap area and spread time through data fitting The relationship formula further clarifies the influence of the relative position of the wood structure building on the spread of fire.The research results show that the temperature and CO concentration in the ignited wood structure building are different in the time when the data is monitored.With the relative position change,the spread of the fire in the ignited wood structure building has a lagging phenomenon.The relationship between the overlap area and the time for the entire wood structure building to be ignited and the time for the exterior wall to be ignited is an inverse proportional function,which can effectively describe the relationship between the relative position of the wood structure building and the spread of fire.Based on numerical simulation again,a fire model with fire points located in the middle wood structure building and corner wood structure building was designed to study the influence of the three fire partition shapes of rectangle,triangle and arc on the spread of fire.Through analysis,it is found that whether the fire point is set in the middle of the wood structure building or the corner of the wood structure building,setting the fire compartment in an arc shape can effectively curb the spread of fire.Finally,a fire hazard evaluation index system for wood-structured buildings is established.The entropy method and catastrophe theory are used to calculate the fire hazard mutation membership of the building group.The introduction of data fitting makes up for the shortcomings of traditional catastrophe evaluation that has too high evaluation value.The initial calculation result is 0.943,and the result after data fitting is0.613,and its hazard level is moderately dangerous,in line with national standards.According to the research content and the risk evaluation results,the protection of wooden buildings.