Three‐Dimensional Rupture Patterns of the Rock Mass With Closed Beddings Under the Blast Loading

The existence of structural surfaces such as closed beddings renders significant anisotropy of the natural rock mass to stand out, and change the propagation process of the blast stress wave, which materially influences the failure mode of the rock mass under the blast loading. The indoor three‐dimensional blasting experiments are carried out for the rock masses with different dip angles and closed bedding groups. The rupture characteristics of the postblast specimen and the distribution patterns of three‐dimensional cracks are compared. The blasting process of the rock mass with closed beddings was inverted using the numerical simulation software AUTODYN, thereby revealing the effects of dip angles and groups of closed beddings on the propagation of stress wave and the three‐dimensional rupture as a result of the blasting of rock mass. Results showed that the dip angles of closed beddings influence the distribution patterns of blast‐induced cracks. With increases in the dip angle of bedding, the three‐dimensional cracks are more likely to propagate and penetrate into the rear portion of the bedding surface. The radial stress induced by the stress wave on the back‐blast surface is increasing and the shear stress gradually decreases, making the rupture mode of the closed bedding dominated by tensile rupture. With increases in the number of bedding groups, the superposition of reflected and transmitted waves across the beddings affects the stress concentration of cracks, and the spatial distribution of three‐dimensional cracks is more scattered. With increases in the number of bedding groups, the explosive energy consumed on the bedding surface continues to increase, resulting in a gradual decrease in the energy transferred across the rock mass beddings. In turn, the explosive energy can hardly continue to accumulate on the back‐blast side.