The numerical simulation of permeability rules in protective seam mining

The protective seam mining has become one of the most important measures of preventing outburst hazard in the deep outburst coal seam. The comprehensive study of gas permeability change rules and gas seepage rules of the protected seam close to the protective seam in the mining process of the protective seam need to be carried out. Based on the current researches, the secondary development of flow model using FISH language is embedded in FLAC3D. Combined with the in situ conditions, the permeability changes in the process of protective seam mining are simulated by the modified models. Based on the above information, the seepage of gas is analysed, seepage path of pressure-relief gas and the distribution of gas pressure in protected seam are obtained. The simulated results provide the theoretical foundation for guiding the field practice and the field data analysis also confirm the correctness of the model.