Control Techniques for Gob-Side Entry Driving in an Extra-Thick Coal Seam with the Influence of Upper Residual Coal Pillar: A Case Study

In multi-seam mining, the residual coal pillar (RCP) in upper gob has an important influence on layout of roadway lower seam. At present, few papers have studied characteristics surrounding rock gob-side entry driving (GED) with different widths under RCP. This research contributes to improving recovery rate extra-thick seam this condition. The main contents were as follows: (1) mechanical parameters and mass obtained using laboratory experiments coupled Roclab software. These substituted into established roof structure mechanics model derive breakage position RCP, rationality calculation results was verified by borehole-scoping. (2) Based numerical simulation, evolution laws lateral abutment stress working face at relative distances RCP studied. FLAC3D used study whole space-time law deviatoric plastic zone GED during retreating periods various (3) plasticization factor P introduced quantify subdivisions rock, so better evaluate bearing performance which enabled a more effective determination reasonable width. field application showed that it feasible set up 8 m below targeted support techniques could effectively control deformation.