## 1 Introduction  
Defects, including fissures, holes, and joints of various sizes and types, are frequently observed within the surrounding rock of roadways (boreholes) during tunnel engineering activities. The spatial distribution and geometry of these defects significantly impact the mechanical properties of the roadway's surrounding rock [1, 2]. Extensive research conducted by scholars both domestically and internationally has demonstrated that defects play a pivotal role in inducing damage to the surrounding rock of roadways [3, 4, 5]. To enhance the control effectiveness of the roadway's surrounding rock-containing defects, it is imperative to understand the influence mechanisms of different defect forms on the mechanical properties and damage modes of rock masses containing boreholes. Consequently, researchers have comprehensively investigated the mechanical behavior, damage evolution, and crack propagation characteristics of rock masses featuring holes, fissures, and other defects (in this paper, the term \"fissure\" is used to denote a pre-existing crevice defect in the rock, and the term \"crack\" is used to denote cracks and damages that occur during loading). In indoor experiments, the literature [6, 7, 8, 9, 10, 11, 12, 13] explores rock samples' mechanical properties and crack propagation characteristics with prefabricated fissures or holes under compression loading. [PERSON] [14] investigated the mechanical properties of sandstone with holes and fissures in uniaxial compression and found that the strength of the sandstone was affected by hole diameter and defect symmetry. [PERSON] [15] monitored the cracking behavior of specimens using digital image correlation (DIC) and acoustic emission. [PERSON] [16] introduced a combination defect of circular holes and single fissures within a sandstone slab. They discovered that the strength parameters of the combined defective sandstone under uniaxial compression decreased as the dip and length of the fissure increased. Several researchers have conducted numerical simulations to understand the mechanical behavior of rock masses containing defects such as fissures, holes, and joints. [PERSON] [17] used the granular flow program PFC2D (Particle Flow Code 2D) to simulate uniaxial compression for sandstones with hole-type trident fissures. Their study revealed that the fissure length had the most significant effect on the peak strength of rock samples with this type of defect. [PERSON] [18] investigated the applicability of DIC and the granular flow model (Bonded Particle Model) to the mechanical behavior of natural rock masses containing defects. They found that the Bonded Particle Model (BPM) accurately simulated the location of crack initiation and the type of agglomeration detected by DIC. [PERSON] [19] compared the effectiveness of DEM (Discrete Element Method) and XFEM (Extended Finite Element Method) in simulating crack sprouting and extension in jointed rock masses. Their research showed that DEM could simulate all cracks during rock fracture, while XFEM could only simulate wing cracks (a crack pattern that extends outward in an arch on both sides of the crack). [PERSON] [20] and [PERSON] [21] performed uniaxial compression numerical simulations of rock masses containing defects of different morphologies and types using PFC2D, demonstrating that the fissure angle could alter the specimen's internal stress field, affecting the rock mass's mechanical properties. The synthesis of previous studies reveals that numerous authors have conducted in-depth discussions on the geometric form and spatial distribution of fissures surrounding boreholes, including aspects such as the number, length, angle, and distance of these fissures.