| Usually, there is a large number of mined-out area in underground mining at steep thintungsten ore veins, if these goaf are not promptly treated, they may threaten the safety of themine production. Therefore, the stability analysis and control measures of gobs areparticularly important.This research was done in Taoxikeng mine, goaf stability was the research object, on thebasis of investigating and organizing relevant information, on-site monitoring, theoreticalanalysis and ANSYS, FLAC3D software, goaf stability was comprehensively analysed. Themain contents and conclusions are as follows:（1）The basic information provided by mine and data gained by in-site investigationwas collected and sorted out. By organizing and summarizing the distribution of gob groups,empty size, shape, geometric parameters, first hand materials of the mine was gained, whichlaid groundwork for the next step.（2）Determination of physical and mechanical parameters of rock. Laboratory rocktests were conducted on two main rocks(quartzite, metamorphic sandstone) in the mine,we gained the necessary parameter values of the two rocks, such as compressive strength,tensile strength, elastic modulus,etc.Rock parameters were adjusted through the elastic wave,M.Georgi Act and the experience Reduction. Mechanical parameters of rock mass weregained, which provides reliable rock mechanical parameters for subsequent numericalsimulation.（3）Based on the engineering background of goafs, theoretical analysis was carried outon the goaf stability. the pillar and roof of goaf was analysed theoretically. structuralmechanics model of pillar roof strata was constructed and the best security value wascalculated.The results show that when stope roof damage occurred, the maximum width of thestope roof is10.67m, limit long span is41.6m, and the pillar width best security value is3.5m.（4）The field empty area was monitored. pillar, rock stress, displacement on the scenewere monitored by using photoelastic stress meter, section of roadway convergenceinstrument, multi-point displacement meter at156m,106m height levels.The results show thatthere is stress concentration in some goafs and significant ground pressure activity, but stressvalue is not large, basically in a stable range. There will not be a large area of subsidence and stress concentration in short-term.（5）Numerical simulation was used to analyse ground pressure distribution of goafs atdifferent height levels.I used AUTOCAD and ANSYS software to establish athree-dimensional model. With the FLAC3D software, I analysed the stress, displacement,shear, footwall rock,plastic zone and safety degree around pillar, roof and surrounding rockof goaf at at different height levels.Thus,the distribution of ground pressure around goafswere gained.The results showed that with the extension of mining depth, the stress,displacement and plastic area to significant increasing trend. There are obvious groundactivity at156m,106m height levels, while most goafs are in stable condition, particularlyfrom the point of cloud security degree. yield phenomenon occurs at part of the rock pillarwith, then shear failure may occur.（6）The process of tail sand filling goaf was simulated by using FLAC3D software.The cloud results of goaf before and after filling the empty area were compared, indicatingstress followed a significant downward trend and deformation was effectively controlled afterthe empty area was filled which provides a reliable basis for the actual processing of minegoaf. |
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