Research On Key Technologies For Safe Mining Of A Fluorite Deposit Under The River

The safe mining of mines is an important issue of underground mining in mines,especially for mines that are close to the surface and have relatively complicated surface conditions,more attention should be paid to the technical research on their safe mining.This article combines the actual mining situation of Gannan fluorite mine,adopts numerical simulation,theoretical analysis,on-site monitoring and other methods to carry out technical research on the safe mining of the mine,which has important practical significance for the safe and efficient mining of the deposit.(1)In order to obtain the physical and mechanical parameters of the mine rock and the insitu stress of the mine area in order to provide the calculation parameters for the numerical simulation,the rock core is taken at the mine site for indoor rock mechanics test research and acoustic emission test to determine the in-situ stress,and the BQ is used on the basis of the onsite structural plane investigation Method and RMR method are used to classify and evaluate the rock mass.The RMR evaluation result is that the quality grade of the rock mass in the mining area is grade ?,and the quality of the rock mass is good.The acoustic stress method determines the stress regression equation,which provides a basis for the numerical simulation of stress inversion.(2)In order to obtain the optimal ratio of the mine tailings cemented filling body,the tailings were tested for physical properties,including particle size composition,particle unevenness coefficient,permeability coefficient,mineral composition,etc.,and different The slump of the concentration of tailings was tested in laboratory.Through the analysis of the strength test of the cemented backfill in the room.The relationship between the mechanical parameters of cemented backfill and lime-sand ratio,filling concentration,curing time was obtained,and the sensitivity of the factors affecting the strength of the backfill was analyzed.The filling body parameters of this ratio are used as numerical simulation filling material parameters.(3)In order to study the surface deformation law of the deposit mining and the stress situation of the surrounding rock under the river after the deposit mining,the method of using numerical simulation supplemented by on-site stress monitoring was used.The results show that in mining and filling condition 3,the maximum Z displacement of surface settlement is 5.86 mm.Filling the mined-out area has obvious effect on improving the surface stability.At this time,the surface structure meets the safety regulations.Set up numerical simulation settlement monitoring points at 8 main locations of surface rivers.In the case of mine filling,the settlement of surface river monitoring points is basically zero.The on-site stress monitoring reflects the safety of numerical simulation mining and filling.From the overall monitoring data,the stress value at the monitoring point as a whole is small and has little fluctuation,indicating that the mine is stable during the monitoring period of about six months.(4)In order to optimize the most safe and reasonable stope structure parameters for mining,the 15 kinds of stope structure parameters were preliminarily determined based on Mathew's theory and elastic mechanics small deformation thin plate analysis method.Factors such as stress,displacement,plastic zone,and recovery rate are given weights,and the numerical values of each factor in each scheme are obtained through numerical simulation,and then the priority is sorted.Finally,the stope structure parameters of the safely mined deposit are obtained.