The Influence Of Open-Pit Stripping Blasting On Nearby Mine Structures

In this paper,based on the goaf governance project of A coal mine in Haibowan District of Wuhai City,the north of the governance area is located within the boundary of No.16coal seam of A Coal Mine,and the southwest is adjacent to B Coal Mine,in order to improve the regional ecological environment and make full use of resources.Open-pit stripping and backfill reclamation were adopted for treatment,and residual coal resources were recovered at the same time.Open-pit stripping was mainly based on blasting,with an area of about0.2616km~2.The nearest horizontal distance to the northwest of the boundary of the stripping area is about 50 meters,and the vertical depth is 160 meters.There are water silos and pumping rooms of Well B coal mine.130 meters from the nearest horizontal distance to the northern boundary of the stripping area is the ventilation room of A coal mine.In order to analyze the impact of boundary stripping blasting on the vibration of two coal mine structures A and B,this paper established the vibration analysis model of prospecting boundary stripping blasting,and optimized the blasting scheme after analysis.(1)In the process of analysis and optimization,the particle flow discrete element program(PFC)was used to measure the macro and micro mechanical parameters of stratum rock mass through the laboratory mechanical experiment and internal calibration test of the program.The non-reflective boundary was established,and the damping was set,and the numerical analysis model of boundary step blasting was established.The application of load and the formation of cracks during blasting are realized by simulating block blasting.(2)Second for blasting scheme of milliseconds differential blasting,this paper use PFC simulation,two hole blasting point to measure the peak moment just determine peak speed not stack differential intervals for 25 ms,and the differential interval blasting scheme is given just match,so this article depending on multiple hole blasting is composed of many single hole blasting section.Through numerical simulation test analysis,the vibration speed of ground wind machine room caused by single hole blasting in the original design scheme is 11.35cm/s,and the vibration speed of underground hydraulic tunnel is 18.29 cm/s,both of which have exceeded the safety vibration speed of the building in the blasting safety regulations.(3)When the vibration velocity of two structures is optimized,the step height must be reduced by 1 meter for each 10%reduction of the single hole charge to achieve reasonable blasting effect.The result of such optimization test is that when the single hole charge is reduced by 70%and the step height is 5 meters,the peak vibration velocity of ground wind machine room is 4.17cm/s.The peak vibration velocity of the underground hydraulic tunnel is 8.95cm/s,at which the vibration velocity of the structure is within the safe range,indicating that the optimized blasting scheme will not affect the structure adjacent to the mine.