Study on the law of ground pressure obliquity effect with gently inclined thin to medium thickness phosphate body from open-pit to underground
Based on the specific geological and mining conditions of north deep orebody mining area in N0.-two pit-head of Jing Ning phosphate of Yunnan phosphating group limited company, the stability of stope roof and surrounding rock, the law of ground pressure activities and the characteristics of mining failure and movement rules of overlying strata were systematically studied by the FLAC3D numerical simulation, under different condition in the process of deep phosphate underground mining. The results showed that: (1) the equilibrium state of the original stress field in the stratum was destroyed, which cause the redistribution of stress, during the process of underground mining. The overlying strata stress was divided into three stages, which contained unloading, bearing stress concentration and restoration of residual stress, by the influence of mining. (2) with the increase of dip angle of ore body, the overall range of the overburden unloading and concentrated area in stope were decrease at the same excavation space, and the ground pressure activity tends to moderate on the whole. The related results can provide some reference for the underground mining project of phosphate mine belongs to Yunnan phosphating group limited company and the phosphate mine with the similar conditions.