Blasting Crater Test Law under Different Resistance Lines Based on DEM-PBM Method

In open-pit blasting project, the minimum resistance line (W) determines the dominant direction of blasting energy release and the maximum direction of rock velocity. This parameter is the core factor controlling the blasting action range, crushing effect and throwing path of the rock. Based on discrete element method-population balance model (DEM-PBM) coupling numerical simulation method of blasting crater, field blasting crater test was carried out through multi-scale modeling and test data collaborative analysis. The rock breaking law of blasting crater test under different minimum resistance lines was studied in order to optimize blasting parameters and improve blasting efficiency and safety. Based on the comparison of numerical simulation results, the blasting expansion area at 20 ms increases by 70.33% compared with that at 5 ms when W=1.05 m, and the blasting expansion area increases by 11.42% when W=1.85 m. By comparing the throwing effect of fragmentation under different minimum resistance lines, the throwing effect is the best when W=1.05 m. According to the results of field blasting crater test, when the length of the resistance line increases, the volume of the blasting crater becomes smaller, and the volume of the blasting crater is the largest when W=1.05 m, which is similar to the blasting cavity expansion law obtained through numerical simulation. The fractal law of fragmentation size in field blasting was analyzed. When W=1.05 m and the depth of blast hole is 1.2 m, more rock blocks are thrown, the fragmentation distribution is moderate, and the throwing effect of broken blocks is the best. This study provides reference for the optimization of field drilling and blasting parameters.