90 / 2023-06-14 17:56:17

Numerical Simulation Study on Depressurization Effect of Protective Layer Mining in Rock Burst Dangerous Coal Seam

Protective layer mining,PFC numerical simulation,Overburden force chain,Pressure relief effect,Factor analysis

Protective layer mining is an important regional measure to reduce pressure and prevent rockburst. In this paper, numerical simulation is used to reveal the mechanism of protective layer pressure relief, analyze the reasons for the rock burst danger at the working face of the protected layer 203 in the Kuan’gou coal mine, and study the influencing factors of the protective layer pressure relief effect. The research results show that after mining the upper protective layer, the high overburden arch force chain structure transfers most of the load to the outside of the goaf. The low collapse and broken rock mass block the transfer of the remaining load, reducing the load of the coal and rock mass below. The inhomogeneity of overburden collapse causes the pressure relief zone and compaction zone under the protective layer. The stress in the pressure relief zone decreases linearly with 0.08MPa/m, and the stress under the compaction zone gradually approaches the original rock stress. The local stress concentration and hydraulic support load increase in the protected layer working face mining result from the combined effect of the increased spacing of the protected layer and the high strength of the interlayer lithology. The hydraulic support load in the numerical analysis is in good agreement with the field observation data, proving the simulation results' reliability. Many interesting factors were also studied in detail, including the mining height of the upper protective layer, the mining range, the coal seam spacing and the lithological strength between the coal seams. Based on the simulation results, the principle of working face arrangement below the protective seam is given. This study enriches the theory of protective seam mining and provides a basis for evaluating the pressure relief effect of working face and safe mining under similar conditions.