It is the theoretical basis for the prevention and control of coal and rock disasters to reveal the occurrence mechanism of mechanical response of coal and rock in stope. The transient characteristics of the spatial structure of overlying strata and the mechanical response of coal and rock in different regions under the action of pressure are studied by similar simulation experiments. On this basis, the elastic foundation beam model is established to analyze the flexural deformation response of hard rock strata under the influence of structural transient. Combined with the numerical simulation method, the step change characteristics of overlying strata stress field before and after the fracture of hard rock strata are compared and analyzed, and the influence mechanism of combined deformation of hard rock strata on the mechanical response of coal and rock in stope is studied. The results show that the breaking of hard rock strata will change the spatial structure of overlying strata. The basic roof and key strata will undergo flexural deformation response due to the change of mechanical constraints in the transient region, and the principal stress state of coal and rock will change within its influence range. Under the influence of structural transients, the symmetrical flexural deformation law of the key stratum makes the overlying strata stress field produce symmetrical step-change characteristics. The third principal stress in the middle of the overlying strata above the goaf changes to both sides, which makes it produce the step-change law of decreasing in the middle and increasing on both sides. The intensified sinking deflection deformation of the key stratum after weighting leads to the positive step change of its internal principal stress, while the rebound deflection deformation of the main roof makes its internal principal stress negative step change, and further changes the stress state of coal rock within its influence range, resulting in the decrease of stress concentration and the migration of peak position. Therefore, the mechanical response of the hard rock strata under the transient influence of the spatial structure of the overlying strata changes the original state of the stress field of the overlying strata, and plays the role of bearing the weight of the overlying strata, which is carried by the stress arch structure formed by the basic roof of the equilibrium state before pressure to the key strata of the equilibrium state after weighting. The results of this study have important theoretical reference significance for the prevention and control of coal rock dynamic disasters.

Clarifying the dynamic mechanism of rock pillar fracture and its rock burst-inducing mechanism is fundamental for the prevention and control of rock burst disasters in steeply inclined extra-thick coal seam groups. In this study, field monitoring, theoretical analysis, and numerical simulation were combined to investigate the rebound vibration behavior and rock burst-inducing mechanism of fractured rock pillars, and corresponding mitigation measures for rock pillar-induced rock bursts were proposed. The results indicate that instantaneous rock pillar fracture induces reciprocating rebound vibration behavior within the coal seam rock pillar, causing the velocity, displacement, and strain energy density of the rock pillar to remain in a persistent fluctuation state. Meanwhile, periodic mutual conversion between strain energy and kinetic energy occurs throughout the vibration process. During any vibration cycle, the rock pillar cannot recover to its initial equilibrium position, resulting in a sharp increase in the loads acting on the floor side of the B3–6 coal seam and a significant decrease in the loads acting on the roof side of the B1–2 coal seam. Consequently, the B3–6 coal seam remains subjected to transient dynamic loading, whereas the B1–2 coal seam experiences transient unloading after rock pillar fracture. This asymmetric transient loading mechanism is identified as the intrinsic reason for the higher rock burst proneness of the B3–6 coal seam. Based on the dynamic response characteristics of the stope coal rock system, staggered-level mining of the B1–2 and B3–6 coal seams and slotting presplitting in the B3 roadway were proposed as mitigation measures for rock pillar-induced rock bursts. When the stagger distance of the working face increases from 25 m to 100 m, the stress drop of the B3–6 coal seam is 22.9%~28.7%. When the slotting depth of the rock pillar increases from 25 m to 80 m, the stress of the B3–6 coal seam decreases by 9.88%~24.1%. These findings provide theoretical support and engineering guidance for rock burst prevention and control in steeply inclined coal seam.