The Numerical Simulation of the Pressure Law and Control of the Hard Roof Face in the Far Field

Controlling hard roof plate breakage and destabilization to ensure a sufficient mine pressure is difficult using conventional underground pressure relief methods, since it is located far above the coal seam. This paper investigated the ground fracturing technology used to control the mine pressure at the working face caused by hard top collapse, using the working face of Tashan 8106 as an example. Finite element software and its global embedded cohesive unit approach, the fluid-structure coupling theory, and the fracture mechanics theory were used to construct a numerical calculation model of hydraulic fracturing during coal rock excavation. The calculation results revealed an initial hard top plate pressure before the fracturing of about 52 m, while the error rate of the initial pressure step was 0.07% compared to the actual measurement results, verifying the simulation's accuracy. At a prefabricated fracture spacing of 16 m, the initial incoming pressure step distance was reduced from 52 m to 24 m after the hard roof surface fracturing, while the peak vertical stress at the coal seam working face decreased by 40.59%. It effectively reduced the mine pressure at the working face caused by the cross fall of the roof, which was more conducive to safe mining. The research in this paper provides theoretical guidance for the control procedures of these types of roof slabs.