Study On Migration Characteristics Of Key Strata Of Overburden And Its Influence On Mine Pressure In Extra Thick Coal Seam Mining

Thick and extremely thick coal seam is abundant in China,and its proven coal reserves and production has accounted for more than forty percent of the coal resources,which further highlights its mining value and application prospects.As the coal seam mining height increases,the fracture height of the overlying strata layer increases accordingly,and the strata behaviors of the working face becomes more intense.Taking the 8203 and 8202 working faces of Tongxin Mine as the research background,this paper studies the movement characteristics of several key strata overburden on the working face of extremely thick coal seam and their influence on the strata behaviors in the stope by means of field measurement,numerical simulation and physical simulation.According to the comparison between the actual rock movement measurement of the 8203 working face and the support resistance curve,it is found that not only the breaking motion of the first key strata affects the mine pressure during the mining of extremely thick coal seams,but also the simultaneous breaking motion of the main key strata in the far field and the key strata in the near field The mine pressure has an impact,and the mine pressure is more intense.According to the TV peeping results of the ground drilling in 8203 working face,it is found that the position of the hole-blocking hole in the extremely thick coal seam mining shows a "step jump" phenomenon,and the location of the fault occurs mostly at the interface between the key strata and the lower soft strata.According to the TV peeping results of the ground drilling in the 8202 working face,it was found that when the working face was pushed through the borehole,the overall trend of the rock strata displacement in the borehole was from top to bottom.After the working face was pushed through the borehole,the borehole moved and moved away,the main trend of layers and collapse is bottom-up.Numerical simulation analysis of the overlying rock migration characteristics at different intervals between the main key strata and the coal seam shows that the larger the interval between layers,the smaller the delamination and rotation deformation of the overlying rock strata block,and the smaller the impact of the main key strata appears to the pressure of the working face.The physical simulation study reveals that the key strata of extremely thick coal seam mining show the characteristics of stepwise breaking and synchronous breaking.At the same time,it verifies the dynamic development process of extremely thick coal seam mining overburden rock migration.The above research results have certain guiding significance for the safe and efficient mining of extremely thick coal seams under similar conditions.This paper contains 40 figures,11 tables and 82 references...