Optimization of Drilling Pressure Relief Parameters in the Working Face of Shaiqihe Phosphate Mine
Rock burst is a major technical challenge that troubles the safe mining of the Shaiqihe phosphate mine.The pressure relief parameters of the borehole in the mine don't match the stress distribution of the surrounding rock,and the pres-sure relief effect needs to be improved.Taking the +80 m working face of the mine as the research object,numerical simulation is used to analyze the changes in stress and elastic energy of the surrounding rock of the excavation roadway under different borehole pressure relief parameters.The optimal pressure relief drilling parameter scheme is explored,and the Gu-Tao rock burst criterion is introduced,calculate the ratio of maximum principal stress to uniaxial compressive strength,evaluate the rock burst level before and after optimizing the pressure relief drilling parameter scheme,and verify the pressure relief effect of drill-ing.The research results indicate that as the drilling depth increases,the stress in the surrounding rock of the tunnel first de-creases and then increases.When the drilling depth is 10 meters,the maximum tensile stress is the smallest;While maintaining the same number of boreholes,if the spacing between boreholes is too small,the pressure relief areas formed around the bore-holes overlap,and the overall pressure relief range is limited.If the spacing between boreholes is too large,the pressure relief areas formed between each borehole cannot play a synergistic pressure relief role.When the spacing between boreholes is 1.1 m,the maximum tensile stress is the smallest;The larger the drilling diameter,the smaller the stress concentration in the sur-rounding rock;After optimization,the maximum principal stress of the pressure relief drilling parameter scheme decreased by 14 MPa,and the risk level of rock burst decreased from moderate to no rock burst.The research results can provide reference for the selection of pressure relief drilling parameters in similar mines in western Hubei.
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