Study on the Stability of Coal Pillars in a Gob-Side Two-Entry Arrangement of Different Layers in Fully Mechanized Caving and the Zonal Linkage Control of "Heteromorphic" Surrounding Rock

To solve the problem of considerable deformation of the tailgate in a fully mechanized caving face, the position of the main roof fracture line is first obtained by theoretical calculation, combined with the results of a similar simulation test and numerical simulation analysis. The width of the section coal pillar in the tailgate is determined to be 11.5 m. Based on the distribution characteristics of deviatoric stress and the plastic zone of surrounding rock, combined with the location characteristics and geological conditions, a new zoning control design approach is proposed, a "two pillars, three zones, and three parts" arrangement for the surrounding rock of the tailgate. The targeted two-entry support design is carried out following common engineering practices. Mine pressure monitoring data were used to verify the results of the new two-entry design. The comparison shows that the supporting technology can effectively control the considerable deformation of the surrounding rock, improving stability for regular mining production.