Therefore, extensive studies have been conducted to explore the fracture problems of hard rocks, with the most complete ones being tests, field monitoring, and numerical simulation of the fracture problems of marble in the deep-buried diversion tunnel of Jinping II Hydropower Station and Lac du Bonnet (LdB) granite in the Underground Research Laboratory (URL) of the Atomic Energy of Canada Limited (AECL) [19; 20; 21; 22]. In underground engineering, excavation through hard rocks under high-stress conditions breaks the original stress balance state, resulting in a brittle failure in the surrounding rock mass near tunnel faces, mainly manifesting as tensile fracture. With continuous excavation advancement and stress adjustment, the fracture of the surrounding rock mass develops from the surface to the inside, mainly exhibiting a shear failure mechanism. The fracture problem in hard rock underground engineering can be broadly divided into two categories: static fracture (e.g., spalling and slabbing) and dynamic fracture (e.g., rock bursts). The main influencing factors include geological conditions and engineering factors. Among them, in situ stresses and discontinuities play a decisive role, according to which the failure modes of surrounding rock mass can be classified as structure control type, stress-structure control type, and stress control type [23; 24]. The excavation of rocks in underground engineering significantly disturbs the rock mass medium, leading to the formation of a generalized excavation-affected zone near the tunnel face, which can be typically classified into three sub-regions: an excavation disturbed zone (EdZ) in the inner area, an excavation damage zone (EDZ) in the middle area, and a highly excavation damage zone (HDZ) on the surface of the cavern [25; 26]. Basalt, which is a typical volcanic rock, is a significant geological environment material for engineering construction in Southwest China, particularly in terms of the diversity and complexities of its mechanics at Baihetan Hydropower Station [27; 28]. [PERSON] et al. and [PERSON] et al. systematically studied the influences of meso-defects, such as amygdala, holes, and hidden cracks, on the macro-mechanical properties of basalt, including its deformation, strength, and failure characteristics, through laboratory tests, numerical simulations, and statistical analyses. In addition, the size effect of the geometry and mechanics of basalt containing meso-defects has been explored [29; 30; 31; 32; 33]. [PERSON] et al. [34] obtained the distribution characteristics of discontinuities in basalt found in the dam site near Baihetan Hydropower Station by conducting a field data statistical analysis, through which the corresponding DFN model was established to analyze the geometric size effect. The fracture evolution laws, failure modes, and deformation characteristics of the surrounding rock mass during the underground cavern excavation at Baihetan Hydropower Station were systematically analyzed by numerical simulation, geological survey, and field monitoring, thoroughly revealing the failure mechanisms [35; 36]. In addition, the size effect, anisotropy effect, unloading effect, and constitutive model of columnar-jointed basalt with special structural characteristics have been explored through various methods [37; 38]. The multiscale mechanical properties and failure mechanisms of geotechnical materials with complex structures have been challenging issues in the field of geotechnical engineering. On the one hand, due to the complexity of the structural characteristics of natural rocks, the results of rock samples with small sizes in laboratory experiments may be different from those obtained through in situ tests, while in situ tests on samples with large sizes have disadvantages such as difficult testing, high cost, data dispersion, and poor reliability. On the other hand, the mechanical behaviors of basalt are mainly studied through conventional laboratory tests, field monitoring, and numerical simulation.