Abstract: To mitigate the impact of large-scale blasting construction on adjacent sensitive structures and to further enhance controlled blasting techniques under constrained conditions, a case study is conducted on the construction project of the No. 2 shield launching shaft of the Guifengshan tunnel on the newly built Zhuzhou-Zhaoqing high-speed railway. Based on the safety requirements of deep shaft blasting adjacent to high-voltage transmission towers and a 500 kV substation, a detailed vertical-layered and horizontally-zoned blasting scheme is developed. The scheme integrates pre-split blasting, main charge hole blasting, and contour blasting, along with vibration attenuation and control measures. The feasibility of the blasting plan and vibration control methods is verified through empirical formulas and experimental testing, including safety checks of key blasting parameters and test blasting analyses. Monitoring during construction confirms the effectiveness of the blasting control. The findings indicate that: (1) The proposed blasting design and control techniques are well-suited for deep shaft excavation under complex site constraints. (2) Both empirical vibration formulas and field tests demonstrate that the combined blasting and vibration mitigation approach is feasible, with vibration velocities at the transmission tower and within the substation remaining below the safety thresholds of 2 cm/s and 0.6 cm/s, respectively. (3) Field monitoring also confirms that shaft and structural settlements stay within allowable limits, and vibration near the ultra-high voltage substation does not exceed critical thresholds.

Key words: ultra-deep shaft, ultrahigh-voltage substation, blasting vibration speed, power facilities, pre-split blasting