Application of Controlled Blasting Technology for Shield Bedrock and Orphan Rock in Mixed Strata

In the construction of shield tunneling in composite strata, the presence of bedrock and orphan rock has significant constraints on shield tunneling. The compression of unbroken orphan rock and strata can not only cause ground collapse and deviation of the shield machine from the excavation trajectory, but also lead to severe wear of the shield machine cutterhead. This paper takes the treatment of bedrock and boulders in a certain interval in Fuzhou as an example. From the geological conditions of the interval, the hazards of bedrock and orphan rock, the main reasons for the formation of bedrock and orphan rock, blasting parameter design and main process parameters, blasting based on five aspects of effect, the blasting treatment methods of bedrock and orphan rock are analyzed. A reasonable blasting plan and optimal borehole spacing parameters were proposed, effectively addressing the impact of high-strength bedrock and orphan rock in composite strata on shield tunneling construction.