To investigate the dynamic instability mechanism of surrounding rock in deep, rockburst-prone coal seams, a Split Hopkinson Pressure Bar (SHPB) system was utilized to carry out dynamic impact compression tests on Rock–Coal–Rock (RCR) composites featuring four different seam dip angles, namely 0°, 15°, 30°, and 45°. We systematically analyze incorporating high-speed imaging, the mechanical properties, energy evolution, and progressive failure characteristics of the composites under various strain rates. The results indicate that the dynamic compressive strength and elastic modulus of the composites exhibit a significant strain-rate hardening effect. With the increase in the dip angle of the coal seam, the compressive strength of the specimen decreases accordingly. Specifically, the range of 15–30° is identified as a critical transition zone where the failure mode shifts from matrix-dominated bearing to interfacial slip instability. At an impact pressure of 0.12 MPa, the compressive strength drops by 36.9% within this interval. Furthermore, the energy distribution is profoundly modulated by the geometric characteristics of the interface. As the dip angle increases, the degree of wave impedance mismatch at the coal–rock interface intensifies, leading to a sharp rise in the reflected energy ratio (up to 80.7%) and a pronounced attenuation of transmitted energy. Notably, the dissipation energy per unit volume increases with the dip angle, revealing that interfacial sliding and frictional work become the primary energy dissipation pathways under large-inclination conditions. High-speed camera monitoring confirms that the instability mechanism shifts from axial splitting/tension to an interfacial shear-slip mode as the dip angle increases. These findings provide a scientific reference for the stability evaluation of roadway surrounding rock and the prevention of dynamic disasters.

To address the engineering challenges of frequent flexural deformation and instability of composite roadway roofs and the difficulty in accurately controlling the support strength range during deep coal mining, this study takes the soft–hard interbedded composite roof of the working face in the West No. 1 Mining Area of Shuangyang Coal Mine in Shuangyashan as the engineering background. Typical fine sandstone (hard rock) and tuff (soft rock) from the on-site roof were selected to prepare layered composite specimens, and indoor four-point bending tests were conducted. Combined with theoretical calculations, strain monitoring, and acoustic emission (AE) real-time localization technology, the regulatory mechanisms of three key factors—lithological combination, loading rate, and span—on the flexural mechanical properties, deformation and failure modes, and fracture evolution laws of layered composite rock masses were systematically investigated. The research results show the following: (1) The flexural performance of layered composite rock masses is dominated by the interlayer interface effect. Their flexural strength is 46.7% and 41.1% lower than that of single hard rock and soft rock specimens, respectively, and the competitive mechanism between interface slip and delamination fracture is the core inducement of strength deterioration. (2) The strength and deformation characteristics of layered composite rock masses exhibit a significant loading rate effect. When the loading rate increases from 0.002 mm/s to 0.02 mm/s, the flexural strength decreases by 51.8% and the mid-span deformation deflection reduces by 50.1%. High loading rates will exacerbate the deformation mismatch between soft and hard rock layers, trigger premature failure of interface bonding, and inhibit the full development of structural plastic deformation. (3) Increasing the span significantly optimizes the flexural bearing performance of layered composite rock masses. When the span increases from 170 mm to 190 mm, the flexural strength increases by 65.7% and the mid-span deformation deflection synchronously increases by 65.7%. A large span can extend the flexural deformation path, promote the coordinated deformation of rock layers, and suppress local stress concentration. (4) The flexural failure of layered composite rock masses is dominated by Mode II shear cracks, while single-lithology specimens are mainly dominated by Mode I tensile cracks. Loading rate and span significantly change the crack propagation mode and energy release law. This study establishes a calculation method for the equivalent flexural stiffness of layered composite rock masses and reveals the mesoscopic mechanism of flexural failure of heterogeneous layered rock masses. The research results can provide a theoretical basis and experimental support for the optimization of support schemes and the prevention and control of roof collapse hazards for composite roofs of deep coal mine roadways.

Aiming at the technical problem of asymmetric large deformation of mining roadways under the influence of fault tectonic stress and excavation disturbance, and taking the return roadway of the left first face of 14^# coal seam in the East No.2 Mining Area of the Pinggang Coal Mine as the engineering background, this research on the deformation mechanism and control technology of a near-fault roadway was carried out by combining on-site monitoring, theoretical analysis, numerical simulation and on-site practice. The results show that under the superposition of fault tectonic stress and excavation disturbance, the surrounding rock presents asymmetric deformation characteristics of fault sidewall > roof > floor > mining sidewall, with the roof-to-floor convergence peak of 991 mm and the two-side convergence peak of 968 mm; the critical instability range of the near-fault roadway is nonlinearly negatively correlated with the surrounding rock Geological Strength Index (GSI) and nonlinearly positively correlated with the disturbance factor (D). The critical instability range of this roadway is 3.44 m, and the peak values of stress and deformation of pillars during the excavation and mining are concentrated 0~4 m from the sidewall; the pillar width is linearly negatively correlated with the stress peak and nonlinearly negatively correlated with the deformation peak. When the pillar width is greater than 16 m, the stress superposition effect of the fault and mining is weakened, and the surrounding rock deformation tends to be stable. Based on the deformation mechanism, a control scheme of “coal pillar size optimization + surrounding rock grouting modification + high-strength anchor cable strengthening” was proposed, which optimized the pillar width to 16 m, adopted grouting reinforcement, and added long and short anchor cables to form a high-strength active support system. On-site practice shows that after the application of this scheme, the two-side convergence and roof-to-floor convergence of the roadway are reduced by 82.4% and 84.5%, respectively, compared with the original support; during the mining period, the two-side convergence is 397 mm and the roof-to-floor convergence is 484 mm, realizing the safe and stable operation of the roadway and the efficient mining of the working face. The research results provide a theoretical basis and engineering reference for the control of asymmetric large deformation of typical near-fault roadways.