Study On The Demarcation And Combustion Mechanism Of Large Area Coalfield Fire

Coalfield fire area combustion mechanism and fire area demarcation technique have been studied in this thesis when utilizing theoretical knowledge including combustion science, hydromechanics, elastic mechanics, rock mechanics, and measuring etc; volatile combustion and carbon combustion of coal seam has been analyzed physically, from which it concludes the maximum shear stress distribution discipline in the ore mass at hanging wall and foot wall of coal seam in the coalfield fire area under the function of deadweight. By utilizing rock cracking process software RFPA2D, numerical simulation-based calculation has been conducted to the rock mass failure mode at hanging wall and foot wall caused by combustion in the coalfield fire area, and the mode and process of earth surface sinking caused by development of combustion have been presented. Characteristics of gas flow in the coalfield fire area have been analyzed; through simulated calculation with FLEUNT software, this thesis points out distribution of inlet air zone, outlet air zone, high-temperature zone on the ground, fire source, high-pressure zone, zone with the maximum airflow speed, zone with the maximum inlet air speed and etc. The discipline that the relation between temperature and time during the process of coal fire extinguishment complies with the quadratic polynomial has been brought forward, and three fire area demarcation methods (demarcation as per rock movement, characteristics of air flow, and monitoring data) have been proposed.