## 5 CT Scan Analysis  
To comprehensively and accurately analyze crack propagation within the fractured rock, researchers employed CT scanning technology to examine the specimens after uniaxial compression. Figure 8 presents the three-dimensional crack patterns of the specimens, along with cross-sectional slices at the front, middle, and back positions. These slices provide an intuitive visualization of the direction, length, and width of the internal cracks as well as the interrelationships between different cracks. Figure 8: 3D fracture pattern and CT scan section of the specimen: (**a**) 0 mm specimen; (**b**) 5 mm specimen; (**c**) 10 mm specimen. It can be observed from Figure 8 that variations in the hole and fissure spacing significantly influence the crack propagation path during rock failure. For the 0 mm specimens, two primary fissures gradually expand on both sides of the hole alongside the loading orientation, eventually passing through the holes and the lower fissures. As the cracks approach the center of the specimen, the angle between the two fissures increases. The upper fissure shifts progressively from the center to the sides of the specimen, and the failure phenomenon becomes more severe at the rear of the specimen, with the crack width increasing significantly. For the 5 mm specimens, cracks primarily initiate at the rock bridges near the front slice and extend along the direction of the fissure arrangement. At the central slice, anti-wing fractures develop at the external tip of the lower fissure, extending upward until they reach the specimen's edge. Toward the rear of the specimen, the cracks converge in the upper right part, forming a localized fragmented area. The failure pattern of the 10 mm specimens is relatively simpler. From the surface to the center, the crack propagation path remains largely unchanged, and a shear fracture zone is formed along the pore arrangement path, extending from the upper right-hand side to the bottom left. In summary, as the horizontal spacing between the holes and fissures increases, the crack propagation path in the hole-fissured sandstone transitions from a complex, tortuous pattern to a simpler, more regular path. The spatial distribution of new cracks shifts from disordered to more orderly. Figure 9 displays the CT scan section images of the 5 mm samples in the vertical direction (front, middle, and back) and the horizontal direction (upper and lower rock bridge positions) under different wetting-drying cycles. As shown in the figure, before the wetting-drying cycles, the sample exhibits relatively complex failure characteristics. The surface of the sample features a penetration crack composed of tensile and tensile-shear mixed cracks, and an anti-wing crack forms internally, extending through the lower cracks and pores and continuing upward to the end. The cracks in the rock bridge region display a pattern of transverse and longitudinal intersections. After the wetting-drying cycles, the internal anti-wing cracks gradually weaken and even disappear, the shear failure characteristics of the specimen become increasingly prominent, and the number of secondary cracks decreases. The cracks in the rock bridge area transition from the original complex failure state to the complete disappearance of transverse cracks, leaving only longitudinal cracks. This indicates that dry-wet cyclic damage affects the crack propagation morphology of the rock, causing the cracks to evolve from a complex shape to a simpler one. The failure mode gradually shifts from tensile-shear failure to shear failure, and a simple crack network structure forms in the inner region of the rock bridge. Through an analysis of specimens with different pore distances, it is found that the change in the distance between pores significantly affects the crack path of rock failure.