Study on quantitative relationship between mining parameters of lower protective layer and protection effect

The analysis of protection effect is an important basis for the determination of mining parameters and the design of pressure relief gas drainage scheme in the protective layer mining project. In order to analyze the influence of different mining parameters on the protection effect of the protective layer during the mining process, the mathematical relationship between the mining parameters and the protection effect of the lower protective layer was studied by using statistical analysis method, and the numerical simulation method was applied to verify the analysis. Based on the statistical analysis of the sample data of 16 lower protective seam mining mines, it is determined that the protective seams at mining heights of 1.5, 2.0 and 3.0 m with the change of relative interval, the parameters of the original rock stress, permeability coefficient and gas pressure of the protective seam have a quadratic function relationship with the mining parameters of the protective seam. The COMSOL numerical simulation method reveals that when the protective layer has a height of 1.5, 2.0, 3.0 m and the relative layer spacing is 15, 20, 30 and 40 times, the permeability coefficient of the protective layer is increased and the original rock stress is reduced. The two research methods have obtained the same trend of functional relationship,and further indicated that scientific nature of the relationship between mining parameters and protection effect functions established by statistical analysis.