(2) The method of caving the surrounding rock may be either a natural caving method or a forced caving method. The natural caving method is not used much because of the specific conditions in China. Any conditional condition should make it fall naturally. The forced caving method is used more in China.
(3) The basic conditions for using the caving method are: the surrounding rock and the surface are allowed to fall.
The two operations of caving surrounding rock and pillar mining should generally be carried out simultaneously. The project of collapsed surrounding rock (drainage chamber, blasthole, etc.) must be completed before the mining column is reclaimed. When the blast is broken, the pillar is first collapsed, and then the surrounding rock is collapsed. (One first, one later).
The caving rock forms a cushion in the upper part of the mining stage to protect the safety of the production work. The height of the collapsed rock cushion should generally be greater than the thickness of the ore body (generally greater than 15 to 20 meters).
For steeply thick and extremely thick ore bodies, empty areas are formed after mining. In addition to the requirement of a rock cushion with sufficient thickness, it is necessary to open a "skylight" in an appropriate place. The goaf is connected to the ground to prevent the damage caused by the strong impact of the sudden collapse of the surrounding rock.
For the mining of gently inclined and inclined ore bodies, the cushion formed by the collapsed surrounding rock is often lost in the lower part of the ore body and cannot be moved down with the falling of the working face. Therefore, in the mining, there should be a planned interval. the stone slate roof caving, rock continue to add cushion.
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