Investigation On Protection Range In Exploiting The Upper-protective Coal Seam Under The Igneous Rock

At present,coal and gas outburst is the main problem to trouble the safety production in the coal industry.The control of the coal and gas outburst has become a future security technology of realizing the coal industry's green mining,and mining protective seam is the most valid and economical regional prevention measures.This paper analyzes the main mining technology and geological factors on the discharging pressure the scope of protection and the influence of the shape.and it takes vital research about the upper protective layer roof existing ignore rock's influencing the extent of protection,by the "key stratum" theory to research that the ignore rock is the key stratrum controlling the strata movement.Combined with plasticity theory and the elastic theory to research that the ignore rock restricts the upper protective layer ming's protection.Through the "regulation" and plasticity theory and "four zone" theory, the analysis shows that the protective coal seam is in the new damaged zone.This paper takes the recognized and effective standards about the discharging pressure to get the Haibei Haizi upper protective layer ming's standards:when the protective layer's the maximum principal stress is less than8.18Mpa, it is in the protective state.When the protective layer's inflation deformation is greater than8.1mm,it is in the protective state.This paper established numerical model and concluded that the protective layer on layer is in the process of mining stress distribution and inflation deformation law of the coal seam, and the study finds that the extent of protection and the discharging pressure level are obviously less than the results of no igneous rock.Through inspecting the experiment about upper protective layer ming in huaibei haizi mine, combined with the theoretical discharging pressure and the result of the numerical simulation, the extent of protection after upper protective layer ming is got.At the same time,The investigation results show that the permeability coefficient in the extent of protection is300times than the not discharging pressure coal. All the investigation results show that the protective coal seam in the extent of protection is protected,the outburst dangerous has been eliminated.The first work-face in the9th coal seam mined successfully.