金川镍矿岩体移动与开采稳定性研究

The two major issues in mining industry are work safety and protection of ground environment when carrying on underground mining activities. Cut-and-fill mining method is increasingly applied in China owing to its advantages of controlling ground pressure and protecting the ground environment effectively. However, some cut-and-fill mines such as Jinchuan nickel mine which has big ore body, broken rock mass and high geostress have unique characteristics on the law of ground pressure and rock mass movement that distinguish from other mining methods. There are still many problems unknown and it is necessary for the further analysis. In this dissertation, vast field survey, geology trenching and relative data analysis are carried out. The distribution of ground fissures and the correlation of the fissures with the location of underground ore body is presented. Using of monitoring data by three-dimension fissure meter and GPS in Jinchuan Deposit Ⅱ, the rule of the surface deformation and the reason of ground fissures generation are analyzed. It is shown that the stress redistribution in surrounding rocks resulting from mining, the existence of the void space underground and the influence of on-going mining activities are three main reasons for the occurrence of ground fissures. Based on actual section planes of No.1 ore body, a large-scale 3D model is established. By this model, the complete process of excavation and filling is simulated and the law of rock mass movement and stability caused by Cut-and-fill Mining is studied. According to simulation results, it is concluded that the deformation of ground surface is still going on developing; the region of subsidence on the ground surface is similar with a circle; the area on the hanging wall side is larger than one on the lower wall side; the contour plots show the centre of subsidence lay on the hanging wall side and the position is near the ore body boundary of 1150m and 1250m where ore body is the thickest. Along strike-line of Jinchuan Deposit Ⅱ, the deformation at the middle of filling body is larger than that in the two sides. Because of the irregular ore body, stress concentrates at the boundary of ore body. With the process of excavation and filling, the high stress release and the stress focus disappear on the hanging wall side. The cut-and-fill mechanism is studied based on monitoring data and numerical simulation. The functions of filling body are discussed. In this dissertation, it is concluded that the stress of filling body is just 2MPa, but the stress of surrounding rock mass is 20MPa. We study the surface movement influenced by the elastic modulus of backfill. The minimal value of the elastic modulus of backfill which can guarantee the safety production of cut-and-fill mine is obtained. Finally, based on the real survey results of the horizontal ore layer and numerical simulation, it is indicated that the horizontal ore layer has destroyed. Key words: cut-and-filling mining, 3D numerical simulation, field monitoring, rock mass movement, cut-and-filling mechanism, the elastic modulus of backfill, the horizontal ore layer

金川镍矿充填法开采引起地岩体移动和地表变形研究

Cut-and-filling stoping becomes more and more important in mining industry for the advantage in protecting environment and its adaptability. However, there is less research in the movement of rock mass and the ground displacement caused by the mining method. In this paper, based on relevant geological and geotechnical test data, the strata movement and the ground displacement of Jinchuan nickel mine are studied comprehensively. The main achievement in this paper can be drawn as follows. Geologic conditions of mining area No.2 of Jinchuan Nickel mine are summed up and influential factors of the movement of rock mass and the surface displacement are analyzed. For recognized the shape of orebody No.l, three-dimensional model is established with 3D Studio MAX software. Based on reconnaissance trip, the monitoring data of GPS and ground fissures in mining area No.2 of Jinchuan Nickel mine are discussed. Then, the rule of the surface displacement and the reason of ground fissures generation are preliminary analyzed. The characteristic of ground movement, surrounding stress and strain in the process of excavation and backfilled is research and analyzed with the method of numerical simulation. The rule of the movement of rock mass and the surface displacement in mining area No.2 of Jinchuan Nickel mine is summed up. The influence of the movement of rock mass and the surface displacement by the dip angle of orebody No.l in mining area No.2 is examined and then the strata movement and the ground displacement is predicted.