Numerical Study On The Unsteady Temperature Field Of Coalfield Fire Area

China is one of the most serious coal fire disaster countries. Not only coalfield fire consumes a lot of coal resources, but also causes serious environmental and ecological problem, producing a large number of poisonous and harmful substances. The origin and development of the coalfield fire area is a complex dynamic process, so building mathematical model of coalfield fire evolvement process, and simulating the unsteady temperature field of coalfield fire area, can deepen the understanding of the development rule of coal fire, and provide theoretical support for fire preventing and extinguishing.By using the TG-DSC synchronous thermal analyzer, the whole process of coal from the low temperature oxidation process to the combustion process was tested. Based on the experimental result, relationships between the reaction rate/burnout time of coal and temperature/oxygen concentration were obtained by q/m method and C-R method. Then oxygen-poor oxidation and combustion mathematical model of coalfield fire area was establishing.Evolvement process of coalfield fire area was analyzing from multi-field coupling and unsteady characteristics. Based on mechanical coupling and parameter coupling, improve the existing mathematical model for coal fire, and establish mathematical model of coalfield fire multi-field coupling including seepage field, temperature field, chemical group field, solid deformation control equation and the main parameters coupling connection.According to mathematical model above, modeling occurrence and development of a coal fire area of Xinjiang and analyzing the temperature field evolution. The results showed that after a long time of the low temperature oxidation, local region of remaining coal reached high temperature where the oxygen consumption rate of coal increased sharply. When it got to a certain critical temperature, the reaction rate was controlled by the oxygen supply. Then high temperature zone moved gradually to the windward side, and temperature increased to 1000? quickly when it was close to the air inlet. After the remaining coal of high temperature burnt out, fire approached to the deep, and the highest temperature maintained about 1000?, while the distribution of temperature anomaly zone had an elliptic form, which was mainly dominated by burning-out zone, and combustion center was near the right focus of the ellipses, low temperature anomalies was in front, so roof strata temperature anomalies was relatively lagging behind to the center of combustion. So coal seam below the roof rock temperature anomaly area detecting by drillings may not be the burning area, but rather burn-out area.Furthermore, the effect of covering the surface crack on the temperature in coalfield fire area was discussed under the condition of different width of crack. Without regard to new inlet and outlet channels formed by thermo-mechanical effect after covering the cracks, the development of fire area can be controlled by covering the air outlet crack when width of air inlet crack was relatively small; when width of air inlet crack was relatively large, the development of fire area can't be controlled only by covering the air outlet crack, because the circular flow appeared at air inlet crack which provided a small amount of oxygen for combustion zone, in this case, both inlet and outlet cracks should be covered so that achieving the purpose of controlling fire area development.