RESEARCH OF STEPPING PRESSURE AND CONTROL OF NEAR FIELD ROOF OF TASHAN COAL MINE BASED ON NUMERICAL SIMULATION¹⁾

The hard roof of coal seam is directionally weakened by hydraulic fracturing technology, which can effectively control the stepping pressure distance and reduce the risk of accidents. Based on the cohesion model and the secondary development technology of the finite element platform, a numerical calculation model of coal seam mining before and after fracturing is established, the roof collapse law and its influencing factors are analyzed, and the fracture spacing design is optimized. The results show that the stepping pressure span has a positive correlation with the roof thickness and strength, and a negative correlation with the buried depth. Prefabricated fractures in tensile stress concentration areas can promote the crack initiation and propagation. Geological parameters of each rock layer should be carefully determined, as well as the location of stress concentration areas, to design the fracture spacing for controlling the stepping distance economically and effectively.