Study on collaborative control of “roof-rib” dual pressure relief in gob-side entry driving under superimposed strong mining-induced stresses

Aiming at the control difficulty of large deformation driven by different mechanisms in the solid coal rib and the coal pillar rib of gob-side entry driving under the influence of superimposed strong mining-induced stresses from opposing mining and excavation in thick coal seams, a comprehensive research approach combining theoretical analysis, numerical simulation, physical similarity simulation, and field industrial tests was adopted. The main conclusions are as follows: ①The mechanisms of large deformation driven by different causes were revealed: the "superimposed mining stress-driven type" for the solid coal rib and the “superimposed overlying strata structural rotation-driven type” for the coal pillar rib. Based on this, a “roof-rib” dual pressure relief collaborative control technology was proposed. ②A comprehensive control scheme was formulated, integrating pre-splitting roof cutting on the gob side, internal pressure relief and anchoring synergy in the solid coal rib, and steel shed-cable coupling in the coal pillar rib. Specifically, the roof cutting parameters include a height of 10m, an elevation angle of 90°, and a cutting hole spacing of 0.6m; the large-diameter pressure relief boreholes feature a starting depth of 6m, a length of 4m, a spacing of 3m, and a diameter of 1m. ③The collaborative control scheme must be implemented no later than 30m before the intersection of the opposing mining and driving faces, covering a total implementation length of 80m within the strong superposition zone. ④Numerical simulations demonstrate that the stress concentration degree of the two ribs is significantly reduced by 44.1% after the adoption of this technology. Field strata behavior monitoring indicates that the convergence of the roadway roof-to-floor and the two ribs is reduced by approximately 74% and 77%, respectively, compared with the original scheme. The research results can provide an important reference for the surrounding rock control of other roadways subjected to strong mining-induced stresses.