Abstract:
Based on the engineering background of upper protective seam mining in Yadian Coal Mine, the rockburst prevention and control mechanism under upper protective seam mining conditions was investigated. Theoretical analysis, numerical simulation, and field measurements were adopted to analyze the roof structure characteristics and surrounding rock stress evolution of the protected seam after upper protective seam mining, revealing the rockburst prevention principles of upper protective seam mining. The results indicate that the deformation, fracture, bedding separation, and dilatation of roof and floor strata induced by protective seam mining reduce the surrounding rock stress in the protected seam working face. Additionally, the roof structure of the protected seam is modified, decreasing the likelihood of high-energy vibrations caused by overburden fracturing and forming a pressure-relief structure that dissipates seismic energy. This mechanism achieves pressure reduction-shock absorption-energy absorption for the protected seam working face, effectively lowering its rockburst risk. Numerical simulations demonstrate that, compared to non-protective seam mining, the roadway surrounding rock stress in the protected seam decreased by 2.0-4.0 times before mining and by 2.3-3.5 times during mining, significantly alleviating stress concentration. Field tests verified that after protective seam mining, the maximum horizontal principal stress, vertical stress, and minimum horizontal principal stress were released by 28.2%, 50.4%, and 23.5%, respectively. Compared to non-protective seam mining, the maximum daily microseismic energy, average daily microseismic energy, maximum daily microseismic frequency, and average daily microseismic frequency in the protected seam decreased by 95.7%, 92.2%, 72.7%, and 65.4%, respectively. These findings confirm that protective seam mining effectively reduces surrounding rock stress, suppresses microseismic energy and frequency, and achieves significant rockburst prevention effects.