Research On Coupling Laws Between Fracture Field And Gas Flow Field Of Short-Distance Coal Seams Group And Preventive Technology

The gas disaster of Chinese coalmine is most severe in the world. Gas is one of the most important factors threatening the safety production of coalmine. Especially after short distance protection layer mining, the coal seam permeability improves dozens to hundreds of times, which increases the gas discharging ability. The gas emission of adjacent seams brings more difficulty of gas control.By laboratory simulation, the space-time evolution laws of mining fissure field of short distance seams are researched. The evolution laws between displacement and fissure field are investigated in case of high gas pressure of lower adjacent coal seam.The UDEC3.0 designed for non-continuum simulation was adopted to simulate the dynamic development process of Overlying Strata collapsing when mining protective layer of close distance coal seams. The fracturing or moving rules of floor and overlying strata, as well as the stress and reformative distribution of protective mine layers are concluded with the advancement of protective working face.The pressure relief reservoir and migration rule and overlying strata movement and fissures evolution process are closely related through the theoretical analysis and the numerical simulation. The time-space evolution laws of coal and rock fissure and gas migration law are found in the course of mining. The gas accumulation rule in the upper corner is revealed.The airflow field and gas concentration distribution law of several different working face ventilation systems are studied by the fluid simulation software of Fluent. On the basis of analysis, the Y+Γshaped ventilation style is put forward and the gas preventive mechanism of Y+Γshaped ventilation is revealed.According to the time-space coupling laws between mining dynamic fissure field and gas flow field, a new protective layer gas control model is brought up. Including drainage fracture zone gas along the roof direction as high level treatment measure, Y+Γshaped ventilation in working face as middle level measure, pump pressure relief gas in floor relieved seam as low level measure. Through the cooperation of three measures, the stereoscopic comprehensive management of trinity in the process of gas pressure-relief in short-distance seam groups is realized, and reach the goal of safety mining .