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

Abstract

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.