Study On Construction Of3D Numerical Model Of Coal Spontaneous Combustion Of Stope For Fully Mechanized Caving Mining And Its Application

With the widespread application of fully mechanized caving mining, the coal spontaneous combustion of fully mechanized caving mining in stope has become one of the serious mine disasters, and it has seriously affected the construction of mine that is safe and efficient. The numerical simulation analysis is one of the main research methods for it. So the construction of3d numerical model of coal spontaneous combustion of stope for fully mechanized caving mining is studied in this thesis based on the analysis of coal spontaneous combustion characteristics of fully mechanized caving mining in stope. And the numerical model is applied to study the rules and the control methods of coal spontaneous combustion of fully mechanized caving mining in stope.Based on the importance of thickness of residual coal and voidage of fractured rock to coal spontaneous combustion of goaf, the theoretical analysis method is applied to study thickness of residual coal and voidage of fractured rock. The methods for determining the thickness and the voidage based on the roof pressure and the expansion coefficient of fractured rock are obtained. The experiment of coal spontaneous combustion under pressure is done, and the influencing rule of thickness of residual coal on spontaneous combustion is obtained.Because the top-coal spontaneous combustion of limit equilibrium zone is possible in stope of fully mechanized caving mining, the method of regression analysis, the theory of damage mechanics and experimentation are applied to study width of limit equilibrium zone and permeability of top-coal of fully mechanized caving mining in stope. The method for determining width of limit equilibrium zone and the empirical formula for calculating permeability of top-coal are obtained.According to the analysis on the characteristics of seepage field, concentration field and temperature field of coal spontaneous combustion of fully mechanized caving mining in stope, the3d numerical model of coal spontaneous combustion of stope for fully mechanized caving mining is constructed, and the coal spontaneous combustion of limit equilibrium zone and goaf are simulated under given conditions. Based on the contrast analysis on the actual observation data and the simulation results, the correctness of the3d numerical model and the reliability of simulation results are proved.The3d numerical model is used to analyze the rules of coal spontaneous combustion of limit equilibrium zone and goaf. The relations of air-volume of working face and the heat-up time of top-coal, and the position of high temperature of top-coal, and height of oxidation zone, and width of oxidation zone, and the position of high temperature of goaf, and the heat-up time of residual coal are obtained. At the same time, the relation of oxygen consumption velocity and spontaneous combustion period, the characteristics of three zones division and temperature field distribution of goaf of fully mechanized caving mining are also achieved.The characteristics of coal spontaneous combustion of goaf of E1S6working face in Jiu Daoling mine is analyzed through the3d numerical model, and the nitrogen injection scheme is selected to prevent coal spontaneous combustion based on the characteristics. The efficiency of nitrogen injection is analyzed through the method of numerical simulation. The results of analysis show that the prevention measure can control coal spontaneous combustion of stope. At last, the prevention measure is used in Jiu Daoling mine, and the prevention measure has good control effect to coal spontaneous combustion of goaf. The practicality of the3d numerical model of coal spontaneous combustion of stope for fully mechanized caving mining is proved.