Application of the Technique of Local Grooving Top-caving with controlled Explosion in Disposing the Abandoned-Stope of Dongtongyu Gold Mine

摘要

After 12 a large-scale mining, 430 000 m~2 continuous and gently inclined abandoned-stopes were formed underground in Dongtongyu Gold Mine in Shaanxi Province, China. To prevent hidden danger of air shock wave resulted by the sudden-caving of the roof, a new unified method, the local grooving top-caving with controlled explosion, was applied to dispose the abandoned stope. In this paper, the characteristics of the method, the identification of the location, width and depth of grooving are introduced briefly, and the calculated grooving location is validated by two-dimensional finite element method (FEM). Meanwhile the effective cutting roof is evaluated by the two-dimensional FEM, the acoustic emission (AE) monitoring in the roof of level tunnel and the observation in the disposed abandoned-stope. The results show that the cutting roof nearby 866 m and 966 m levels is reasonable when ore above 750 m level is mined entirely, and the roof stress will be redistributed to more safe situation, and obvious surface subsidence and rock movement may be prevented. Under favorable conditions the roof may fall and fill the abandoned-stopes soon after its roof cutting is conducted, whereas, under many circumstances the roof must experience one or two months then falls and fills the abandoned-stopes. Moreover, the hidden danger of large scale roof sudden falling is eliminated.