After returning to the mining house by the open field mining method, a large number of goafs are left and must be disposed of in a timely manner. With the mining of the ore and the formation of the empty area, the original stress state of the rock mass is destroyed, the stress is redistributed, the stress is concentrated in some parts, and the stress is reduced in other parts. With the deepening of the mining work or the mining of the remaining mines, the volume of the empty area continues to expand. If the concentrated stress exceeds the ultimate strength of the ore or surrounding rock, the surrounding rock will have cracks, and the deformation of the roof, roof and roadway will occur; in severe cases, the pillar will be crushed, the mine will collapse, the roadway will be destroyed, and the rock will move as a whole. The roof is large and large, and the ground is not cracked, sinking and collapsing, that is, large-scale ground activity occurs. When the top plate falls down in a large area, a destructive mechanical punch that also produces a strong crack is an impact. The lighter affected is only the individual stope or stage, and the heavy ones have caused the entire mine to be stopped.
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