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To address delayed roof fracture, severe stress concentration, and strong strata pressure under thick–hard roof conditions, this study investigated the 1014 mining face of Yushuquan Coal Mine. A staged thick-plate model incorporating boundary-condition degradation was established based on Mindlin–Reissner thick-plate theory to analyze the deformation and stress redistribution characteristics of the thick–hard roof during mining. The evolution mechanism of the stress-concentration shell was systematically studied through theoretical analysis, physical simulation, numerical simulation, and field application. The results show that, with mining advancement, the boundary constraints of the thick–hard roof gradually evolve from four-sided clamped support to four-sided simply supported conditions. Meanwhile, the high-stress zone migrates from the goaf boundary toward the central suspended roof region. The stress-concentration shell undergoes a dynamic process of formation, expansion, failure, and reconstruction, and its instability is the main driving mechanism of large-scale roof caving. The plastic zone expands upward in an inverted funnel shape, while acoustic emission signals increase significantly before roof instability and exhibit strong precursor characteristics. Based on the evolution characteristics of the stress-concentration shell, a three-stage coordinated blasting technology was proposed to regulate the overburden load-bearing structure. Field application shows that this method effectively reduces suspended roof distance, caving block size, surrounding rock deformation, and hydraulic support pressure, thereby improving roof stability and mining safety. The results provide theoretical and engineering references for stability control of thick–hard roofs under similar mining conditions.
Xie et al. (Mon,) studied this question.