Monitoring And Analysis Of Stope Stability Under The Co-mining Conditions Of Dual Mining

The second mining area in the west of a mine used to adopt the downward layered cemented filling method with simultaneous stoping of two middle sections for mining.However,due to the accidental collapse of a large area of cemented filling method in the upper middle section,the mining technical conditions have changed.Meanwhile,in recent years,the price of mineral products fluctuates greatly and the mining cost of the filling method is high,so the mine is on the verge of loss.The remaining mineral resources in the upper and middle section are no longer suitable for the mining with the downward layered approach cemented filling method.Combined with the actual production and demand,after a series of in-depth analysis and research,the mine decided to change the remaining ore body in the upper and middle section to the sublevel caving method for mining,while the lower and middle section of the ore body continues to adopt the filling method for mining,thus forming a complex situation of co-mining between the caving method and the filling method in the same mining area.To ensure the stability of each stope is the premise to realize the safe and efficient co-mining of caving and filling method in the Second West Mining Area.In this paper,numerical simulation experiments,microseismic monitoring,stope surrounding rock deformation monitoring and blasting vibration monitoring are adopted to analyze and study the stope stability in the co-mining process of caving and filling method in West No.2mining area.The main work and results are as follows:(1)Using FLAC3D software to carry out numerical simulation of the upper and middle section of the stope stoping with caving method,the time-space evolution law and characteristics of the stope pressure with caving method are found out,and according to the analysis of the stress state of the roadway surrounding rock,it is concluded that the roadway can maintain a good stability when the roadway is stoped with caving method.At the same time,the change rules and characteristics of the stress and deformation of the lower cemented backfill in the collaborative mining process of caving and filling method were obtained through numerical simulation,and the analysis showed that the lower cemented backfill was relatively stable in the collaborative mining process.In addition,the stress state of the interstope columns with the lower filling method is simulated and calculated.The simulation results show that the stress of the interstope columns with the lower filling method does not exceed the bearing strength of the interpillar,and the interpillar is relatively stable.(2)Based on the analysis of microseismic monitoring data,the space-time effect of stope microseismic events in the mining process is determined.The monitoring results show that the rock mass rupture mainly occurs in the roof of the original cemented backfill above the caving area of the upper caving method,which indicates that the roof of the cemented backfill formed by the original filling method in the upper and middle section gradually caving to form the overburden,and the formation of the overburden meets the safety requirements of the caving mining process.There is no obvious rupture event in other areas,and the stope with caving method,the lower cemented filling body and the lower filling method are relatively stable.(3)Based on the monitoring data,the deformation characteristics of the stoping approach in the process of caving were found out.In addition,the monitoring results show that the approach deformation and daily average deformation are small during the stoping period,and the caving mining has little influence on the stability of the rear approach,and the stoping approach with the caving method is relatively stable.(4)Through the analysis of blasting vibration monitoring data,it is concluded that the blasting vibration intensity of the deep hole blasting in the upper ore-body caving method on the cemented filling roof of the lower ore-body filling method is less than that of the shallow hole blasting vibration intensity in the normal production of the stope with the filling method,and the blasting vibration damage effect is smaller.Deep hole blasting in the caving method has no adverse effect on the roof stability of cemented backfill in the lower filling method.Through the above research,the stability of the upper caving stope,the lower filling stope and the lower cemented filling body is analyzed and evaluated when the caving method and filling method are co-mined in the West No.2 mining area.The research results can guide the safe production of the mine.