The area of permafrost worldwide accounts for approximately 20% to 25% of land area. In cold-climate regions of China, which are garnering international attention, the study of low-temperature and moisture effects on rock mass mechanical properties is of significant importance. China has a wide area of cold regions. This research can provide a foundation for China’s exploration activities in such extreme environments. This paper examines the mechanical behavior of rock specimens subjected to various low temperatures and water contents through uniaxial compression tests. The analysis encompasses failure modes, stress–strain relationships, uniaxial compressive strength (UCS), and elastic modulus (EM) of these specimens. Findings reveal that at lower temperatures, the rock specimens’ fracture patterns transition from compressive shear failure to cleavage failure, reflecting a shift from a plastic–elastic–plastic to a plastic–elastic response. Specifically, saturated rocks exhibit a 40.8% decrease in UCS and an 11.4% reduction in EM compared to their dry counterparts. Additionally, in cold conditions, an increased water content in rocks primarily leads to vertical cracking. Under such conditions, saturated rocks show a 52.3% decline in UCS and a 15.2% reduction in EM, relative to their dry state.

Blasting technology is widely applied in various engineering applications due to its cost-effectiveness and high efficiency, such as in mining, transport infrastructure construction, and building demolition. However, the occurrence of cracking in the rear row has always been a major problem that disrupts mining bench blasting. To address this issue, a three-hole simultaneous blasting technology is proposed in this study. Both numerical simulations and onsite blasting experimental testing were conducted. To aid this endeavor, the three-hole simultaneous blasting and the hole-by-hole blasting methods were adopted to comparatively analyze the severity of the damage caused to the original rock and the effect of rock fragmentation in the rear row. The obtained results highlighted that the outcome of the blast produced by the three-hole simultaneous blasting method is satisfactory, with fewer flying stones and concentrated blasting piles required. Additionally, the original rock in the rear row showed no obvious sign of tensile damage and had uniform fragmentation. It was also found that a block size of less than 60 cm accounts for 100%, while a block size of less than 50 cm accounts for 98.7% of the whole blocks, with no large blocks reported. Moreover, a penetrating horizontal crack occurred in the direction of the connection of the blast hole center when the three-hole simultaneous blasting method was adopted. This resulted in a smooth and flat rear part of the rocks at the interface. Compared to the hole-by-hole blasting method, the three-hole simultaneous blasting method improved the effective stress and displacement at each measurement point. At the measurement point directly at the front of the borehole, the maximum effective stress attained 67.9 GPa, and the maximum displacement reported was 31.9 cm. Overall, it was shown that the three-hole simultaneous blasting technology is applicable in similar applications of mine bench blasting, which is conducive to addressing the rear row original rock strain for onsite bench blasting.

To improve the contour quality of smooth blasting in rock tunnels, a comprehensive study was conducted on the initiation behavior of emulsion explosives subjected to axial shaped-charge jet impact under different charging configurations, confinement conditions, and charge spacings through model experiments, numerical simulations, and field investigations. The results indicate that: (1) the axial shaped-charge charging structure significantly enhances the stability of jet-induced initiation, while stronger confinement conditions and shorter charge spacings further improve initiation reliability. Under surrounding-rock confinement, interval charging based on axial shaped-charge liners can achieve reliable detonation transfer between explosive segments; however, the charge spacing must be maintained within an appropriate range. (2) Charge spacing is the dominant factor controlling stable detonation transfer. As the spacing increased from 10 cm to 75 cm, the jet-tip pressure decreased from 3.84 GPa to 0.85 GPa, accompanied by an increase in the critical penetration depth required to establish stable detonation in the acceptor explosive. (3) A novel shaped-charge tube–liner charging structure integrating axial detonation transfer and radial directional rock fragmentation was developed. Compared with the conventional continuous charging structure, the maximum overbreak and underbreak were reduced from 33.7 cm to 9.6 cm, while the maximum damage depth of the surrounding rock decreased from 0.94 m to 0.65 m. These improvements effectively enhanced contour control and minimized blast-induced rock damage, thereby significantly improving the smooth-blasting performance of tunnel excavation. The proposed charging structure provides a promising approach for achieving precise contour control and damage reduction in underground rock engineering.