Study On Damage And Control Of Deep Hole Blasting Impact Backfill

In engineering blasting,the damage caused by blasting impact and damage control have always been an important research topic.Compared with the damage caused by static load,the dynamic damage caused by blasting is more significant.Among them,the dynamic effect of blasting on the backfill pillar in the two-step backstoping process in mines using the stageempty backfill method will induce its instability and failure.Therefore,studying the damage of the backfill pillar after blasting and optimizing blasting parameters according to the damage situation can effectively control the stability of the pillar and reduce the blasting damage.Based on the mining project of Zhongguan Iron Mine,field investigation and analysis are conducted on the geological conditions of rock mass,hydrology and other geological conditions of the mine.Combined with the theoretical research of deep-hole blasting,GDEM software is applied to analyze the damage of backfill pillar caused by blasting in the process of ground falling ore.The selected blasting parameters were used to establish the GDEM deep-hole blasting model,to explore the vibration velocity and stress attenuation law inside the backfill pillar,and to analyze the damage evolution law of backfill and ore house in the blasting process with damage factor.The simulation results show that the impact in the X direction is obviously greater than that in the Y and Z directions.The three hole blasting results in the superposition of stress waves,which makes the blasting vibration rate and stress impact increase and causes greater damage to the backfill.There is a natural gap between the orehouse and the backfill pillar,which leads to obvious attenuation of stress and vibration velocity at the interface,and stress waves are emitted in large quantity at the interface.Flank hole blasting has the greatest damage to the backfill.According to the damage study of deep-hole blasting,the damage of backfill and the blasting effect of ore under the conditions of different side hole spacing and hole diameter are simulated.It can be seen that the damage depth of backfill increases with the decrease of side hole spacing and the increase of hole diameter.The value of side hole spacing/aperture is introduced to fit the correlation curve of damage depth under the condition of charge density of 0.5,0.75 and 1,and the permissible side hole spacing range under different pore diameters is obtained.Therefore,the optimal blasting parameters are selected through the simulation results,and it is concluded that the blasting parameters with a pore diameter of140 mm,a side hole distance of 3.5m,and a charging coefficient of 0.75 can obtain the best blasting effect of ore under the condition of ensuring the stability of backfill.Figure 47;Table 6;Reference 63...