An Approach on the Types and Mechanisms of Water Inrush in Traffic Tunnel Constructions in China

Water inrush is a kind of most common geological hazards during tunnel constructions. Based on a lot of water inrush cases, this paper discusses the types and mechanisms of water inrush during traffic tunnel constructions in China. According to the groundwater source and geological structures of aquifers, tunnel water inrush can be classified into five types, namely, gushing by cutting through surface water, gushing by cutting through an aquifer, water inrush from fault zones, water inrush from Karst pipes, water inrush from other structural fracture zones. Based on case studies and mechanical analyses, the mechanisms of tunnel water inrush are revealed as cutting through and gushing free, hydraulic splitting of fissures, hydraulic fracturing of impermeable rock wall, and static-dynamic disturbance of the discontinuities of rockmasses.