Study Of Processing Measure For Gently Inclined Abandoned Stope Using Numerical Simulation

Abandoned stope disposal is a technological problem widespread in the mining field in our country. In this thesis, according to the condition of Mujia Hill, the method of roof cutting and ore pillar dilapidation is proposed. The main research contents are as follows:(1) According to the systematical summings-up of the method for disposing abandoned stope and theoretical analysis, the unit method of roof cutting and ore pillar dilapidation is presented in this paper. Its main point is: large weakness configuration, e. g. faults is applied or roof cutting is adopted by explosion , together with ore pillar dilapidated within the minimal cantilever roof span , to cause roof to collapse, or ore pillars within minimal roof span are dilapidated, so roof uncontrolled caving is resulted in.(2) The indoor experiment of mechanical parameters of rock is performed to provide a series of mechanical parameters of rock-mass needed in numerical simulation of abandoned stope disposal.(3) The minimal roof span, the minimal cantilever roof span and roof cutting depth are studied by the 3D non-linearity FEM code ANSYS. The analysis result shows that uncontrolled collapse of dolomite roof can be ensured if the minimal roof span of 102 m long at the south (66 m long at the north) or the minimal cantilever roof span of 76.5 m long and roof cutting of 8-11 m vertical depth are adopted.(4) Roof stress-distribution and surface subsidence & rock movement are studied respectively by 3D FEM code ANSYS before and after ore pillar dilapidation and roof cutting . The result shows that abandoned stope disposal can cause the roof to collapse uncontrolled in a short period of time, and the hidden danger of air shock wave caused by roof suddenly caving can be prevent, and mining lawlessly may be also counterchecked. Furthermore, the surface subsidence & rock movement is not remarkable, so subsequent mining safety can be ensured.(5) 3D FEM code EPSCA3D is used to analyze roof stress-distribution and surface subsidence & rock movement respectively before and after roof cutting and ore pillar dilapidation. The result shows that abandoned stope disposal can also make roof cave in a short time. With considering seepage and stress, and the decrease of surface subsidence and rock movement will be resulted, subsequently, mining safety will be ensured .(6) The seepage influence on the surrounding rock is analyzed by using EPSCA3D inthe course of disposal, and the result shows that the influence relates to penetrability of rock-mass and geological condition of mineral-deposit (e.g. the site and dip angle of water-resisting layer . etc. ). The groundwater presents pressure-force in deep level, but presents rising-force to the upper layer. Furthermore, groundwater maybe cause the surrounding rock to loosen and soften after disposal.This research work not only provides a set of referential parameters and processing measure via settling practical engineering problems of Mujia Hill, but also evaluates the stability of surrounding rock scientifically before and after stope disposal. At the same time, it first uses hydromechanical coupling theory to analyze the influence of groundwater during disposal, and contributes to promote further study of abandoned stope disposal.