Theory and simulation investigations on stability control of gob-side entry retaining with coal pillar-backfill body system

• A voussoir beam structure (VBS) model was established to analyze roof stability in gob-side entry retaining (GER), introducing a stability criterion that guides design parameters. • Reducing block B length and immediate roof damage, while increasing coal pillar width, lowers the instability risk of the GER structure. • UDEC simulations revealed that at l=14 m, xb=2.0 m, and water-cement ratio 1.5:1, the coal pillar and backfill body exhibit similar crack damage and maintain stability, achieving better coupling. • Field monitoring confirmed the effectiveness of the CPBB system, with peak stresses of 19.17 MPa (ahead) and 16.14 MPa (behind) in the coal pillar and 12.27 MPa in the backfill body, and floor heave of 380 mm.