Theroy And Technology Of Dynamic Equilibrium For Multilayer Goaf Flow Field

Datong Mining Area has a long history of mining, and the main task of Datong is exploiting the Jurassic and carboniferous system layer which is an easy spontaneous combustion of coal seam group. In the process of mining extremely close distance coal seam group under the condition of "two hard", the goaf is disposed by full caving method after the end of mining upper coal seam. When the lower coal seam is mined, the interconnected goafs upper coal seam resaut in the increase of air leakage passages in mining workig face and then the complex multilayer goaf flow field is formed. Traditional general equalizing method can’t solve this complex problem. This paper made some systematic and thorough research aiming at the problem that a wide range of spontaneous combustion fire on multilayer goaf upper the Jurassic System 0～7 meters extremely close distance and easy spontaneous combustion of coal seam group poses serious threat to the existing mining coal working face in Datong Mining Area.The paper proposes the partical dynamic equivalence theory of multilayer goafs and the balance theory of feedback compensation with multipoint control, and analyzes the gas flow state in goaf according to mathematical method to ensure the gas pressure of mining working face and adjacent goaf in the smallest scope under the circumstance of keeping dynamic balance, and compensates the multiple control points by using centralized control method. And as a result, it avoids mutual influence and the harmful gas such as CO and CH4 is stopped into the mining working face as well as the fresh wind are prevented into the goaf. At the same time, the partical dynamic equivalence technology and equipment in multilayer goaf are researched with the feature of monitoring,controling and regulating pressure by frequency conversion, then apply to Sitai and Majiliang mine combining the technology to preventing and treating coal natural fire such as blocking off, stereoscopic nitrogen injection, the inhibitor grouting and so on. Through practical application, the system normally realizes dynamic equilibrium of dynamic equilibrium between mining working face and multilayer goaf flow field. Poisonous and harmful gas upper the goaf is stopped into the working face as well as the fresh wind is prevented into the goaf effectively. So the safety production can be realized.