Research purposes:A large water bursting happened at the entrance of the tunnel to bring a lot of disasters. The hydro-geological data and in-site observed data were analysed to find out the reasons for the water bursting and sum up the laws of the appearance of water bursting for the purposes of making the remediation schemes for design and construction of the tunnel and avoiding the construction risk.
Research conclusions:The topography junction and lithology interface between mountain watershed consisting of Silurian clastic limestone and mountain slopes consisting of Qixia and Maokou groups limestone were the catchments. The 3# underground river developed in P1q+m stratum where was rich of water with three different types of water-filled layers. They were related to 3# underground river in various degrees. Water inrush brought the water of the underground river into the tunnel. The rechanneled underground river remained the characteristics of 3# underground river, such as pipeline flow, dynamic changes of runoff quantity and precipitation-runoff relations etc. The diversion of the underground river would have a certion impact on the environment, and the silt and stones brought by the water inrush would cause some difficulties in construction, operation and maintenance of the tunnel.