Study on the Behavior of Blasting Crack Propagation under Different Crack Widths

To study the influence of slit width on the dynamic propagation behavior of blast cracks, the digital laser dynamic caustic line experimental system and fractal theory were used to study the propagation laws of blast cracks at six different crack widths. The results show that the length of burst cracks in the cut direction is greater than that in the non-cut direction. With the increase of the slit width, the propagation length of burst crack increases first and then decreases. When the slit width increases to 0.4 mm, the main crack propagation length is the largest, and when the slit width continues to increase, the main crack propagation length decreases. When the slit width is 0.2 and 0.4 mm, the fractal dimension is larger than that of other slit widths, the expansion length of the main crack is longer than that of other widths, and the directional fracture effect of the specimen is better. With the increase of the slit width, the stress intensity factor and velocity peak value of the main crack propagation of the slot shows a trend of first decreasing rapidly, then increasing to the secondary peak, and finally oscillating and decreasing. When the crack width is 0.2 and 0.4 mm, the peak value of the stress intensity factor and the expansion velocity of the main crack are larger than those of other crack widths. The research results provide a certain basis for the selection of slit parameters in actual blasting engineering.