Roof weighting and support of a largely mined shallow coal seam

Abstract

AbstractTo study roof weighting and the support of a largely mined shallow coal seam, the hydraulic support resistances in both small and large periodic weightings were derived by different theoretical formulae. Support working resistances of the 12,401 mining face in small and large periodic weighting were 10,442 and 17,064 kN, which represented a loading-increase coefficient of up to 1.64. Mining cracks were formed up to land surface and were visible to the naked eye, and numerical simulation of roof stratum structure by 3DEC has been proven to be realistic. A 1.2-MPa supporting intensity represented a critical threshold for effectively reducing horizontal displacement and inhibiting rib spalling using FLAC3D. Hydraulic fracturing and micro-seismic monitoring were used to ensure the safety of the 12,401 mining face. These findings can explain the mechanism of mining a shallow coal seam for effective prevention and controlled design. The results show high accuracy and are consistent with reality.