Abstract: Constructing a drainage tunnel next to the highway tunnel with active traffic to “collect” the groundwater can effectively minimize the groundwater inrush in the operating tunnel. To expedite the drainage tunnel construction, part of the active highway tunnel could be utilized as the construction access as well as the multi-process drainage tunnel excavation faces. The blasting excavation is a commonly used tunnel construction method in the high strength rock mass where the machine excavation is not efficient. However, the excessive vibration induced by the blasting excavation might adversely affect the safe operation of the existing highway tunnel. In tis paper, a new segmental blasting method is proposed to resolve the low efficiency, high vibration and potential safety hazards in the conventional blasting excavation method. 

Key words: Highway Tunnel with Active Traffic, Groundwater Inrush, Transverse Tunnel Construction, Blasting Excavation Method, Multi-Process Excavation Method