Application of Shaped Charge Device and Decked Charge in Perimeter Holes of Smooth Blasting

Smooth blasting in tunnel construction needs decked charge in the peripheral holes. However, this charging method has certain limitations and risk of misfire due to the usage of detonating cord together with detonator. So, it is an urgent problem to improve the effect of smooth blasting and ensure tunnel excavation efficiency at the same time. Related research was conducted by field tests, and a new initiation technology of “Shaped device+digital electronic detonator” has been proposed, which was applied to a plateau tunnel. The experimental results show that, compared with the original technology, the powder factor by using the new technology has been reduced by 0.2 kg/m³, the half-hole rate is increased by 5%, and the average charge time is reduced from the original 1.3 h to 1.0 h. The tunnel excavation cycle footage is stabilized, and the cost of consumables is greatly reduced, and it is expected to be widely used in tunnel smooth blasting.