Study Of Multi-field Distribution Characters And Fire Prevention Countermeasures In Goaf Of Complex Caving Model

The paper is to further study the rules of spontaneous ignition in the goaf and controling problem of the spontaneous combustion disaster and gas disaster.For this purpose,we have established the "Double Three" model by taking the 150405 working face of Duanwang Mine as a case study example.In brief,the model is mathematical model of porous media of goaf caving heterogeneous based on optimized 3D"O" type circle,also includes 3D physical model of fully-mechanized goaf under a W-shape ventilation formation of two inlet airways and one return airway.It is on the above basis that we have devoted to consider the gravity and the porosity change of goaf in the vertical direction,and then accomplished the 3D visualization of porosity.The oxygen consumption is obtained from the closed oxygen consumption experiment.Meanwhile,we have worked out a numerical simulation model for the gas pressure distribution,air-leakage field,oxygen distribution and the gas distribution in the goaf via a software FLUENT with UDF(formula of oxygen consumption and porous medium model).In addition,we have finally ascertained that the pressure distribution of goaf and airflow field within the reasonable air-leakage range coincided with the practical cases.Furthermore,we have emphatically analyzed the distribution regularity of gas concentration under considering the different porous medium models.The numerical simulation of the model considering complex caving goaf can be stated in the following way:In contrast,the phenomenon of gas accumulation in the goaf(no drainage)not just appears at the top of goaf,but also floats upward in numerous.And,the width of accumulating zone is after 3 5?40m from the base plate;Meanwhile,the gas accumulation shows high volume fraction;In summary,conclusions mentioned above shows a new law of gas distribution characters,it do have an important guidance for the next study of gas extraction.Secondly,it widely analyzes the different angle of working face for the mingle effect of gas emission and spontaneous combustion "three zones" in goaf;The next analyzes the multi-field distribution charactersof optimized porosity goaf after the gas extraction and obtaines the consistent with actual extraction speed,what is more,the simulation results accord with the measured data,verifying the numerical simulation of practicality and reliability.Finally,the oxygen concentration analysis the distribution regularity of spontaneous combustion "three zone" of goaf.The paper has made security risk assessment for the danger of spontaneous combustion in goaf,which has an oxidation temperature zone with a maximum width of approximately 80 m.Calculation results also demonstrates that the minimum advance degree is 0.68m/d under safe conditions for spontaneous combustion.Through,the relevant numerical analysis and division results of spontaneous combustion"three zones" in goaf proposes preventive measures based on the "three zones"and spontaneous combustion of conventional spontaneous combustion prevention measures.