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Distribution Characteristics of Fragments Size and Optimization of Blasting Parameters Under Blasting Impact Load in Open-Pit Mine

The size distribution characteristics of fragments formed after loose blasting in open-pit mine will directly affect the economic benefits of the mining enterprise. The impact load test of coal samples with pressure ranging from 0.13MPa to 2.0MPa was carried out by using the split Hope Pressure Bar Test System (SHPB). Based on the theory of stress wave attenuation, the relationship between blasting load and coal samples impact test in the laboratory is established. It is concluded that with the increase of impact pressure, the degree of coal samples breakage increases gradually. According to the requirement of blasting quality in open-pit mine, it is concluded that the impact pressure range with good crushing effect is 0.30MPa ≤P ≤0.90 MPa. Based on image recognition method, the fragmentation distribution characteristics of loose deposits of coal seam blasting in open-pit mine are obtained. Combining the impact load test in the laboratory and the fragmentation distribution of coal seam blasting, the influence area of blasting impact fragmentation is divided. According to the research results, two optimization schemes of blasting parameters are put forward and the blasting effect of the two schemes is verified by numerical simulation using ANSYS/LSDYNA. Through field blasting optimization test in open-pit mine, it is concluded that increasing blasting hole spacing and row spacing can effectively control dust pollution and increase massive coal rate.