Dynamic response characteristics and damage calculation method of fractured rock mass under blasting disturbance

The mechanical responses and damage characteristics of fractured rock masses under dynamic loads play a significant role in ensuring the safety of blasting operations. The study employs dynamic finite element method (FEM) to simulate blasting in fractured rock masses, revealing the propagation features of blasting stress waves, the evolution of effective stress and the mechanism of damage evolution around the borehole. Based on the Weibull distribution, a rock damage model was established, which yielded the stress-strain relationship and damage equation for rocks under uniaxial impact. The parameters of the damage equation were fitted through numerical SHPB tests. The results indicate that in the direction of higher initial stress, the stress wave propagates faster, and the development of damage surfaces is more pronounced. In cylindrical charge blasting, the maximum blasting stress occurs in the middle section of the borehole, with limited influence from the charge on the bottom of the hole. Within a range of approximately 2 to 3 times the borehole diameter, the surrounding rock sustains complete damage. While within a range of about 4 to 5 times the borehole diameter, the degree of damage to the surrounding rock decreases rapidly, and beyond this range, the damage to the surrounding rock gradually diminishes.