Abstract：The application of gob-side entry retention by roof-cutting (GERRC) in thick coal seams with composite limestone roofs faces severe stability challenges due to the high-energy, synchronized fracturing of hard strata. To address this, this study investigates the geomechanical mechanisms of roof breaking through integrated analytical modeling and numerical simulation. A static equilibrium model is first developed to contrast the "long key block masonry beam" formed in conventional mining with the "short cantilever beam" structure optimized by roof cutting. Furthermore, a rotational inertia model is introduced to quantify the reduction in kinetic energy transfer during block rotation. Numerical simulations utilizing the von Mises yield criterion are then employed to visualize the evolution of plastic zones and stress redistribution paths. Results demonstrate that directional roof cutting eliminates the synergistic fracture of upper and lower limestone layers, reducing peak abutment stress by 27.5% (from 17.74 to 12.86 MPa). The induced roof subsidence increased by 104.35% (reaching 3.29 m), facilitating effective gangue backfilling and mitigating stress concentration. Field validation of the "cut two, support one" technique confirms the model's accuracy. This work elucidates the coupling mechanism of composite hard roofs, offering a rigorous numerical-analytical framework for pillarless mining in complex strata.
Li et al. (Tue,) studied this question.