Research on complete set of technology for “pressure relief-reinforcement” surrounding rock control in gob-side entry driving with small coal pillars in medium-thick coal seams

In order to solve the problems of large bearing stresses and deformation along the gob-side entry driving roadway of medium-thick coal seam, a complete set of “pressure relief reinforcement” surrounding rock control technology for small coal pillars driving along goaf in medium thick coal seams is proposed, with the main body being “advanced roof cutting pressure relief, opposite anchor cable grouting reinforcement, and auxiliary support in the roadway”. Taking Wulanmulun Coal Mine as the technical background, the key parameters of the gob-side entry driving in the medium-thick coal seam are analyzed by using theoretical analysis and numerical simulation. The results show that the support resistance of the coal pillar and roadside support body is 2 891.2 kN. When the width of the coal pillar is 4 m and 3 pairs of anchor cables are arranged in the small coal pillar, the supporting strength of the small coal pillar meets the requirements. When the steel pipe with Φ194 mm×8 mm in the thickness is used with the C40 grade concrete for auxiliary support in the roadway, the gob-side entry driving roadway can meet the requirements of long-term use. The newly “pressure relief-reinforcement” surrounding rock control technology could strongly decrease the deformations of coal pillar and gob-side entry driving and minimize the plastic degree of the coal pillar. By monitoring the displacement of the surrounding rock in the gob, the “pressure relief-reinforcement” surrounding rock control technology of the gob-side entry driving with medium-thick coal seams and small coal pillars can effectively control the surrounding rock deformation of the gob, and the application effect is remarkable.