Numerical Simulation Study on Pressure-Relief Effect of Protective Layer Mining in Coal Seams Prone to Rockburst Hazard

Protective layer mining is an important regional measure to reduce pressure and prevent rockburst. Based on the engineering background of frequent mining earthquakes in the 203 working face below the upper protective layer of the Kuangou Coal Mine, PFC was used to simulate the mining process of the protective layer and protected layer, and many factors affecting the pressure relief effect of protective layers were analyzed in detail. The results indicate that the arch force chain structure of the high overlying rock transfers most of the load to the outside of the goaf, and the low-caving broken rock strata hinder the transmission of the remaining load, resulting in a decrease in stress below the protective layer. The uneven collapse of the overlying rock causes the stress relief zone and stress recovery zone under the protective layer. The distance between coal seams and interlayer rock mechanical strength led to rockburst beneath the protective layer. Increasing the mining height and range of the protective layer enhances the pressure-relief effect, while increasing the coal seam spacing and rock strength reduces the pressure-relief effect of the protective layer. This study enriches the theory of protective layer mining. It provides a basis for the evaluation of pressure-relief effect and safe mining of working face under similar mining and geological conditions.