Influence of lateral structure and combined support system of split-level entries in the thick seam

In this paper, an innovative mining method of the split-level of external staggered gob-side entry (SEGE) is proposed to solve the serious deformation of traditional entry in the continuous panel and coal wastage in Xiegou Coal Mine. Entries on either end of a longwall panel using the layout are located at different vertical levels within a thick coal seam. In the same panel, an entry (haulage entry) is along the floor and the other entry (air-return entry) is along the roof. Theoretical formula is used to calculate the fracture position of the main roof. The system uses "trapezoidal bottom coal body below the air-return entry (TBCBHE) + fallen rock" to control the rotation angle of key block B in the main roof, and reduces the transmission of stress to gob-side entry in the continuous panel. The influence of lateral structure of the TBCBHE is used to ensure the stability of chain pillar of the gob-side entry in the continuous panel. At the same time, the anchor bolt (cables)-combined support is adopted in different spatial positions of adjacent entries in the adjacent panels to reduce the surrounding rock deformation of the gob-side entry in the continuous panel. Through the on-site application monitoring, the rib-to-rib and roof-to-floor convergences of the gob-side entry were significantly reduced than the previous wide pillar entry.