Propagation features of blast-induced stress waves undergo substantial alterations as they traverse heterogeneous interfaces. In rock engineering, the prevalence of discontinuous structural planes, such as joints and fissures, becomes increasingly pronounced with increasing burial depth. To gain a comprehensive insight into the dynamic response and damage mechanism, an explicit dynamics numerical method incorporating the ALE algorithm and fluid-solid coupling technology was adopted, which allows for precise simulation of the fracture process within jointed rock mass under the combined effects of confining pressure and blasting load. Based on the time-domain recurrence theory, the transmission and reflection coefficients of the stress wave were calculated, and the propagation process and features of the stress wave were then analyzed by the explosion photoelasticity test using an epoxy resin plate. Additionally, the Riedel-Hiermaier-Thoma (RHT) damage model was used to investigate the influence of different joint angles and confining pressures on cracking behavior. Furthermore, the cracks were quantitatively assessed using the FracPaQ program. Finally, the damage mechanism of the jointed rock mass was revealed by analyzing the principal stress distribution and displacement change as well as the dynamic stress intensity factors (DSIFs) of the joint tip. The results show that both the joint and the anisotropic pressure have a guiding effect on crack extension, and the effect of the anisotropic pressure will be weakened by the presence of the joint. For the anisotropic pressure condition, the stress wave transmission and reflection coefficients tended to decrease and increase, respectively, with increasing pressure in the horizontal direction. From the change rule of normal and tangential displacement on both sides of the joint surface, it is found that shear stress is the main cause of tip-wing crack expansion. An analysis of the DSIFs reveals that tensile cracks predominantly contribute to damage at the joint tip during the initial phase of blasting, with shear cracks becoming the dominant form of damage in the later stages.

The evolution and distribution characteristics of cracks in presplit blasting can be significantly affected by the in-situ stress, often leading to issues such as over or under excavation in deep rock masses. In this paper, a theoretical model for presplit blasting under in-situ stress in rock engineering was developed based on the assumption of plane-strain problem of elastic mechanics. The propagation and attenuation of explosion stress waves were analyzed using a combination of Laplace transforms and numerical inversion. Furthermore, the impact of initial static stress on the blasting-induced dynamic stress field distribution in presplitting was examined and discussed. The Riedel-Hiermaier-Thoma (RHT) model in LS-DYNA code was employed to investigate the dynamic mechanical behavior of rock mass, and its material parameters were calibrated by comparing blasting crack patterns and the explosion pressure attenuation curves. Then, the validated model was used to simulate the damage features of rock presplit blasting under both hydrostatic and anisotropy pressure conditions, thereby analyzing the effects of the static stress and the dynamic pressure on the crack extension behavior. In addition, the distribution characteristics of blasting cracks are quantitatively characterized by the Hough transform method. The results indicate that the difficulty in crack coalescence for deep rock presplit blasting is primarily attributed to the reduction of tangential tensile stress caused by the in-situ stress. This prevents the formation of tensile fracture planes between boreholes due to restricted tangential displacements, which was demonstrated by the evolution of circumferential tensile stress and particle displacement vectors. Moreover, a crack coalescence criterion in presplit blasting was proposed to predict whether inter-borehole cracks penetrate based on the damage theory of stress wave superposition, and the relationship between charge diameter and hole spacing under various in-situ stress can guide the arrangement of boreholes, thus improving the presplit blasting effectiveness for deep rock.