Controlled shaped-charge blasting technology for deep underground tunnel engineering

With the rapid development of the economy and society, the demand for mineral resources and energy has increased rapidly. However, it is difficult to improve the efficiency of blasting construction and control the stability of the surrounding rock in deep underground engineering. In this study, the deep underground tunnel of the Tianchi pumped-storage hydropower station in China was considered as the engineering background. Based on the stress redistribution state of the surrounding rock after blasting excavation, the crack propagation effect and dynamic response of the surrounding rock under different controlled blasting methods were studied through theoretical analyses, numerical simulations and in situ tests. The mechanism of directional crack formation was analysed by considering the influence of hole spacing and in situ stress. It was shown that the initial ground stress was conducive to the propagation of the blasting crack in the contour hole of smooth blasting towards the direction line of the blast hole. The test results showed that using controlled shaped-charge blasting methods in the blasting excavation of underground tunnels can improve the utilisation rate of explosives, reduce blasting vibration and achieve a significant effect on directional crack formation. The research results have important engineering significance as they can lead to improvements in the blasting technique, a contour-forming effect of the blasting excavation and control of the stability of the surrounding rock.