Experimental Study On Evolution Law Of Gas And Thermal During Mine Fire Area Sealing

Mine fire is one of the common disasters in the underground mines.When conventional fire extinguishing method fails,the fire area sealing is an effective measure for underground firefighting.In the process of sealing and within a short period after sealed,gas explosion accidents are extremely likely to occur.In order to reveal the mechanism of gas explosion in the process of fire area sealing,this paper,focusing on the working face external fire sealing,carried out the whole-process model experimental study on the evolution law of thermal and gas concentration of before,during and after the sealed the fire area.This paper expatiates on the theories of fire area sealing,analyzes the spatial distribution characteristics of the fire area,develops the model experimental device,and carries out the experimental research on the evolution law of the gas and thermal field in the working face when the fire inlet and return tunnels are sealed at the same time.The results show that:(1)The inlet wind velocity in the fire area presents a nonlinear decreasing trend with the condition of uniform velocity sealing.Before the end of the sealed,the sealing resistance is greater than the original ventilation power,which leads to no fresh air flow into the fire area in the last period of the sealing.The higher the initial wind velocity before the sealing,the faster the sealing resistance increases,and the longer of no wind in the last period of sealing.(2)Shortly after the fire breaking out,the fire and its nearby temperature can detonate the gas.Affected by the amount of air in the sealed fire area,the fire source continued to burn after the sealed,and the temperature of the fire source location decreased slowly,and the highest temperature area in the fire area existed near the fire source for a long time.Before the sealing of the fire area,the temperature of the working face in the fire area is much higher than the goaf.The temperature in the goaf area near the upper and lower corners starts to gradually increase at the end of the sealing,while the temperature in other areas does not change significantly.(3)After the fire area sealed,the temperature in the goaf continues to rise.The higher the initial wind velocity before the sealing and the faster the sealing velocity are,the faster the goaf temperature will rise.In the fire area,except for the fire source,the oxygen decreases slowly in other areas.In the process of the fire area sealing and the short period after the sealed,the oxygen concentration in most areas is higher than that of the de-detonation oxygen concentration.The research results have a certain significance for understanding the evolution law of the thermal and gas concentration in the fire area with the sealed conditions of the fire area,and revealing the mechanism of the thermal power disaster accident in the sealed fire area.