Possible causes of rock shoots in loose unsupported workings on the example of Khibiny apatite deposits
Abstract
The Kirov mine of the Apatit Combine produces a stratum-shaped apatite-nepheline deposit with an average thickness of 150-200 m, located between the ijolite-urtites in the lying side and the ricechorrites in the hanging side. The extension of the deposit is northwestern, 310-320°, dipping at an angle of 30±5°. Protodyakonov strength: ore f=6-8, host rocks f=10-12. Horizontal and vertical excavations are often accompanied by a sudden separation (with a sharp crack) of pieces of rock from the contour and face of the excavation. This phenomenon, called shooting, is observed during excavation both on ore and on rocks of hanging and lying sides. The most active shooting is manifested immediately after blasting operations during the sinking of workings.
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