A Novel Gob-Side Entry Method in China: A Case Study

Abstract

Aiming at the characteristics of conventional gob-side entry in thick coal seam, it is found that the weak bearing capacity of narrow coal pillar leads to the problem of large deformation of surrounding rock. By changing the location of the entries to improve stability of the entries, a mining method of split-level of the external staggered gob-side entry (SEGE) is introduced. In this novel gob-side entry, an entry (air-intake entry) is along the floor and the other entry (air-return entry) is along the roof. The trapezoidal bottom coal body (TBCB) below the air-return entry of each panel has horizontal lateral abutment stress to ensure that the chain pillar is in a three-dimensional stress state. Based on the mechanical and numerical modeling approaches, the horizontal staggered distance in the adjacent panels of external split-level entry is determined as 2 m. Combined with the actual production geological conditions and geomechanical evaluation of mine, the optimum supporting parameters are determined. The compressive stress field is formed in the combined supporting area of split-level entries of adjacent panels to ensure stability. Through the synergy of TBCB below the air-return entry and the combined supporting system of the adjacent entries of the adjacent panel, the SEGE maintains stability of the gob-side entry in the continuous panel to ensure normal coal production.