## 1 Introduction  
With the gradual depletion of shallow mineral resources, resource development is increasingly moving deeper, and the mining of deep resources within 2000 m will gradually become a new trend in resource development [1, 2]. The high in situ stress and complex geological conditions of deep rock masses significantly impact the extraction of mineral resources [3, 4]. The drilling and blasting method is the primary technique for deep mining construction and mineral resource development, achieving efficient rock fragmentation through drilling holes and detonating explosives in the rock. Compared to shallow mineral resources, deep mineral resources are under high in situ stress conditions, which significantly affect the blasting fragmentation effectiveness [5]. The blasting extraction of deep rock masses requires theoretical and experimental investigations that are distinct from those of shallow rock blasting. The blasting fracture of rock is a process of crack initiation, propagation, connection, and the formation of a network of fractures. The study of crack propagation characteristics is fundamental to understanding the mechanisms of rock blasting fractures. Researchers have made certain progress and achieved results in the study of blast-induced cracks in deep high in situ stress rock masses. Relevant experimental studies have shown that the maximum principal stress of the in situ stress field has a guiding effect on the propagation of blast-induced cracks [6]. In a two-dimensional plane, when the magnitudes of in situ stress are the same in all directions, the in situ stress field suppresses both the number and the length of blast-induced crack propagation, particularly significantly affecting the extension of radial blast-induced cracks; when the magnitudes of in situ stress are not equal, radial cracks primarily propagate along the direction of the principal stress [7]. As the principal stress differential in the in situ stress field increases, the propagation direction of the primary blast-induced crack gradually deflects toward the direction of the maximum principal stress [8]. Furthermore, [PERSON] et al. [9] investigated the effects of in csitu stress on the directional crack propagation of a slit charge through theoretical analysis and caustics experiments. They found that the initiation and early propagation of cracks are primarily influenced by the stress distribution around the borehole and the action of the blasting gas, while the later propagation of cracks is mainly affected by the in situ stress field. In the study of the blasting fracture mechanisms of deep rock masses, clarifying the effects of in situ stress on the propagation characteristics of blast-induced cracks is essential. Revealing the three-dimensional damage characteristics and fracture patterns will form the core content of the experimental research. The results of this research will have a direct guiding significance for engineering practice. X-ray computed tomography (CT scanning) technology has significant advantages in studying the internal microcharacteristics of rock masses, such as pore structures and fracture geometries [10]. Its advantages include continuity and non-destructiveness. Therefore, CT scanning has increasingly been applied to studying the damage characteristics of rock masses. [PERSON] et al. [11] prepared a series of cylindrical samples for uniaxial compression tests, reconstructed three-dimensional views from CT scan images for analysis, qualitatively determined the fracture evolution process of Longmaxi Shale, and obtained the quantitative distribution of crack areas during loading. [PERSON] et al. [12] combined CT scanning with three-dimensional reconstruction techniques to study the fracture mechanism of rock with air-decked charges and the effect of the initiation point location on rock fracture characteristics, analyzing the distribution patterns and fracture features of blasting damage in rock samples.