Numerical simulation of shallow buried contiguous seams mining under karst condition

In order to study the mining influence under karst conditions, based on the geological conditions of Qinglong Coal Mine in Bijie, Guizhou, a mining model with karst structure was established, and the effects of mining disturbance, mining speed, mining direction and other factors were simulated. The research shows that the karst structure causes the sudden change of the roof stress, and the sudden change position is more obvious in the boundary between karst and non-karst area; the vertical stress in the coal seam directly below the karst structure is relatively small, but the outer periphery may be larger, disaster prevention should be prepared before reaching directly below the karst structure; upper protective layer mining of shallow buried contiguous seams has a better pressure relief effect on the lower protected layer, but the permeability enhanced effect is relatively limited; properly increasing the mining speed will help alleviate the high-stress state of the roof, but it will also reduce the permeability enhanced effect of the lower protected layer; when the lower coal seam adopts the same mining direction as the upper coal seam, the safety is relatively higher.