Dynamic Instability Mechanism and Stress Staged Evolution of Gob-Side Entry During Cross-Fault Mining for Thick Coal Seam

Abstract

During cross-fault mining, the stress concentration in the surrounding rock of thick coal seam gob-side entry was prone to dynamic disasters. Based on the in-site geological conditions of the No. 6305 coal face of the Xinjulong coal mine, a FLAC3D numerical simulation model was established to research the failure and stress staged evolution of coal pillar in the gob-side entry during cross-fault mining. By analyzing the relation of surrounding rock structure, the mechanical models of different stages during cross-fault mining were established. Furthermore, the mechanical mechanism of coal pillars' dynamic instability under the influence of fault activation was revealed, and the mechanical criterion n was given. The control technology of ‘asymmetric strengthening support + roof cutting and pressure relief’ was proposed and designed. Field practice showed that the maximum roof-to-floor and two-side displacements of the gob-side entry are 249.3 mm and 150.4 mm, and the force of anchor cable is 184.2 kN. This research provided theoretical guidance and reference for the stability control of roadways within the influence range of fault under deep mining conditions.