F-structure model of overlying strata for dynamic disaster prevention in coal mine

The rupture and movement scope of overlying strata upon the longwall mining face increased sharply as the exploitation scale and degree growing recently, and the spatial structure formed by fractured strata became much more complex. The overlying strata above the working face and adjacent gobs would affect each other and move cooperatively because small pillar can hardly separate the connection of overlying strata between two workfaces, which leads to mining seismicity in the gob and induces rockburst disaster that named spatial structure instability rockburst in this paper. Based on the key stratum theory, the F-structure model was established to describe the overlying strata characteristic and rockburst mechanism of workface with one side of gob and the other side un-mined solid coal seam. The results show that F-structure in the gob will re-active and loss stability under the influence of neighboring mining, and fracture and shear slipping in the process of instability is the mechanism of the seismicity in the gob. The F-structure was divided into two categories that short-arm F and long-arm F structure based on the state of strata above the gob. We studied the underground pressure rules of different F-structure and instability mechanism, thus provide the guide for prevention and control of the F-structure spatial instability rockburst. The micro-seismic system is used for on-site monitoring and researching the distribution rules of seismic events, the results confirmed the existence and correct of F-spatial structure. At last specialized methods for prevention seismicity and rockburst induced by F-structure instability are proposed and applied in Huating Coal Mine.