In this study, mechanical mechanism analyses of hole cut blasting and in situ hole cut blasting tests using different cutting programs were conducted to investigate the hole cut blasting mechanism under the influence of complicated geological conditions and its blasting excavation effect. The hole cut blasting mechanism was evaluated under the background of medium‐length hole cut blasting test in a typical coal‐rock roadway in Xiayukou coal mine of Hancheng mining area in Western China to improve the blasting excavation efficiency in coal mine roadways. Test results indicated that the rock clamping action is remarkably enhanced when the depth of medium‐length holes, which are impacted by various complicated geological factors, reaches more than 1.8 m under weak coal‐rock mass conditions. At the same time, the antidrag effect is good when double‐wedge cut blasting is selected, and its mitigation of rock clamping action is reflected through the reduction of rock resistance of phase I hole cut blasting. The enhanced blasting effect is embodied by the footage cycle and forming effect of blasting, and the footage cycle of single blasting increases from 1.6 to 2.0 m, thereby indicating its remarkable economic benefits. The results of this study can provide a reference for hole cut blasting design and mechanism study of weak coal‐rock masses under complicated geological conditions.

Rock fracture mode has practical significance for the prediction and prevention of engineering disasters, and the inversion of fracture mode by the waveform signal not only reduces the experimental error of the mechanical strength measurement but also simplifies the type and quantity of disaster prediction source data. For the relationship between crack mode and mechanical strength, the acoustic emission (AE) waveform signal is studied. Six coarse-grained sandstone samples were tested by uniaxial compression, AE, and scanning electron microscopy. The results show that the number of microhole cracks in rock is positively correlated with tensile-shear cracks and negatively correlated with mechanical strength. The quadratic function regression curve of the proportion of shear cracks and mechanical strength is more realistic. When crack ratio is less than 0.31, the number of shear cracks is positively correlated with the mechanical strength and vice versa. The waveform mutation coefficient $k$ is defined as the overall change description. It is found that the increase of signal mutation has a positive impact on the mechanical strength of rock. The fitting function of crack and the signal mutation near the peak of rock can be divided into six risk zones in a two-dimensional plane. In addition to these exciting results and discoveries, the determination of the number of tensile-shear cracks and its relationship with mechanical strength provide innovative methods and ideas for crack pattern discrimination and rock burst risk assessment of roadway surrounding rock.

To analyze the mechanical characteristics of damaged coal bodies and the mechanisms of evolution and degradation of internal pore and fracture defects under cyclic loads, raw coal containing original pore and fracture materials was selected as the research material. This study investigates the impact of cyclic loading on the mechanical properties of damaged coal and the evolution of flaw structures, such as pores and cracks, within the coal. A micro-fracture size judgment index (C_i) was defined based on fracture volume to determine the dominant macroscopic failure mode in coal bodies. The results indicate that a “hysteresis loop” forms in the loading and unloading curves of each cycle due to cyclic loading. During the cyclic loading and unloading phase, both the loading elastic modulus and the damage parameters of coal samples increase proportionally with the level of loading and the number of cycles. In the constant amplitude cyclic loading and unloading phase, there is minimal variation in the loading elastic modulus and damage parameters of coal samples, indicating their stability. As micro-scale fractures evolve within the coal body, pores with a volume less than 10⁹ μm³ decrease with increasing cyclic loading and unloading during amplification cycles but remain relatively stable during equal amplitude cyclic loading phases. The contribution rate of damage to fractures with a volume between 10⁹ and 10¹¹ μm³ increases with higher load levels and cyclic loading/unloading during both amplification and equal amplitude cycles. The minimum order of magnitude for fracture volume that dominates macroscopic failure in the coal body is determined to be 10⁹ and 10¹⁰ μm³.