Steeply inclined seams buried at dip angles of 35–55° are considered hard-excavated seams in the mining industry. A partial backfilling method based on sub-regional features of surrounding rock deformations and failure and support stability was proposed to realize safe, efficient production, to promote sustainable development of coal mining and disaster prevention in western China. Through experiments, calculations, and theoretical analysis, a mechanical model was established, and governing equations for the deflection curve, bending moment, and rotation were deduced. Results reveal the filling percentage, filling ratio, and working-face dip angle as major factors causing roof failure. The degree of roof deformation decreases with increasing filling percentage, filling ratio, and working-face dip angle. With an increase in filling percentage and filling ratio, the range and magnitude of the stress-concentration zone at a T-junction increase, whereas those pertaining to the stress-release zone in the roof decrease. The stress-arch profile of the roof changes from a single peak to double peaks with reduction arch height. Additionally, the maximum arch height shifts towards the centre with increasing moderation of asymmetric features of stress arches. With an increase in working-face dip angle, stress concentration at the coal-wall head T-junction decreases, and a double-peak stress arch develops. Therefore, in order to obtain the best backfill mining effect, a higher filling percentage is preferred; with a maximum filling value of 0.93, the reasonable range for the filling ratio is 1/3 to 1/2 and the reasonable dip angle of the working face is approximately 35°.

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.

In view of the difficulty of fully-mechanized mining in steeply inclined coal seam with thickness of 4 to 8 m, the horizontal section short wall fully-mechanized caving mining method is innovatively proposed. In the No. 3-3c steeply inclined coal seam of a Coal Mine, the single roadway integrated with excavation and recovery is arranged as working face, the pillar on sides of roadway is recovered ahead by spiral drilling machine, and the top coal is recovered by the vertical and horizontal self-moving supports. The Z-type ventilation is formed by constructing a ventilation roadway along the side of gob. Through theoretical analysis, numerical calculation and physical similarity simulation, the main mining parameters, including sectional height and ratio of mining height to caving height, were determined, and the characteristics of roof movement evolution, floor failure and sliding and the generalization of surrounding rock bearing structure were revealed. The results show that the effect of coal caving is better when the section height is 10 m and the ratio of mining height to caving height is 2.85. The cross-layer multi-ladder voussoir structure is formed by transformation and migration of the critical layer, and the failure and slip modes of floor are extruding-translation, extruding-underdraught and extruding-upthrust in different areas of horizontal sublevel caving stope. Roof, pillar and floor are interrelated to form the Roof-Pillar-Floor (R-P-F) chain structure. When the height of section with three sublevels is 30 to 45 m, the mutual conversion of strong and weak chains between structural units can be cut effectively in mining process, and the impact disaster caused by the roof falling over great extent and the instability of pillar can be prevented. The new mining method proposed and studied above provides the technological and theoretical basis for the safe and efficient production of such coal seams, and is of great significance to the sustainable development of coal in Xinjiang province and even western China.