Grouped Delay Initiation Technology Using Industrial Electronic Detonators in Tunnel Excavation

During the excavation of Paishanchong Tunnel of the Quanmutang Reservoir Project in Hunan Province, blasting operations were conducted under environmentally sensitive conditions, featuring direct undercrossing of Provincial Highway S227 at the portal section and adjacent residential structures. To address these safety challenges, a controlled initiation system utilizing industrial electronic detonators was implemented. Identical category blastholes were cluster-initiated with precisely calibrated millisecond delays between groups. The cutting hole initiation sequence was meticulously designed alongside strict regulation of the advance per blasting cycle. This approach successfully contained peak particle velocities to 7.1722 cm/s beneath the provincial highway and 1.6033 cm/s near residential areas. Field implementation demonstrates that in tunnel excavation and similar underground operations, cluster initiation of homogeneous blastholes with optimized initiation sequencing and delays effectively mitigates blast vibrations while maintaining fragmentation efficiency comparable to simultaneous detonation of identical holes.