Study On Stability Of Mine Pillars In Water-soluble Mining Based On FLAC^3D

Water-soluble mining is a special underground mining method.Solution dissolves ores underground and causes erosion of stope structure to a certain extent at the same time,and many small and medium-sized mines are limited by capital,technology,mining cost and mining scale.There are many unreasonable designs and irregular mining in the process of design and mining.In this paper,the water-soluble mining of glauberite in an underground mine in Sichuan Province is taken as the research object.Findings from field investigations,it finds that in the process of mining,solution has a certain erosion effect on the mechanical properties of pillars,so that the stability of pillars decreases gradually and the stability of stopes can not be fully guaranteed.No supporting measures have been taken for pillars,which will further reduce the stability of the pillar,but also brings great potential safety hazards to the personnel and equipment operating in the tunnel.In order to improve the stability of the mine pillar and further ensure the safety of the stope,the stability of the mine pillar was studied by means of theoretical analysis,mechanical test and numerical simulation.Firstly,the pillar eroded by solution in the stope were sampled,the parameters of rock mechanical properties are obtained by tested in laboratory.Then,the pillar width should be no less than 20 m along the strike and no less than 28 m in the vertical direction by theoretical analysis and calculation.On the basis of theoretical analysis,the gradient was selected,and numerical simulation analysis of FLAC3 D for different pillar widths.It was concluded that the pillar width are 19.6m along the strike and 28.4m along the vertical strike to meet the stability requirements of pillars.According to the analysis results of pillar width,it can be seen that it is extremely unreasonable to adopt uniform pillar width of 10 m at present in mines.Finally,through rock stability evaluation and analogy method,it is recommended to adopt the combination of shell-expanding prestressing hollow grouting bolt + TECCO Net + shotcrete to support the part that has been mined and is being mined at the bottom of pillar roadway.The above measures can ensure that the pillar remains stable after being eroded by solution.