Abstract: In this study, the spatial distributions of stress and fracture fields for three typical underground coal mining layouts, i.e. non-pillar mining (NM), top-coal caving mining (TCM) and protective coal-seam mining (PCM), are modeled using discrete element software UDEC. The numerical results show that different mining layouts can lead to different mining-induced stress fields, resulting in diverse fracture fields. For the PCM, the mining influenced area in front of the mining faces is the largest, and the stress concentration factor in front of the mining faces is the lowest. The spatial shapes of the mining-induced fracture fields under NM, TCM and PCM differ, and they are characterized by trapezoidal, triangular and tower shapes, respectively. The fractal dimensions of mining-induced fractures of the three mining layouts decrease in the order of PCM, TCM and NM. It is also shown that the PCM can result in a better gas control effect in coal mines with high outburst potential. The numerical results are expected to provide a basis for understanding of mining-induced gas seepage fields and provide a reference for high-efficiency coal mining.

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Keywords: Coal mining, Mining layouts, Mining-induced stress field, Mining-induced fracture field, Numerical simulation