Mechanism analysis and treatments of water and stone inrush in Daliang tunnel

Research purposes: During the construction of Daliang tunnel, water inrush happened in the contact zone of the Ordovician limestone and slate at syncline wing, with a flow over 2 300 m3 per hour. Three times of larger-scale water and stone inrushes occurred during the treatment, which seriously impacted the safety of tunnel construction. As a result, it is significantly important to ensure the construction safety, by ascertaining the local hydrogeological condition and analyzing the reason of water and stone inrush, and adopting scientific and rational treatment measures. Research conclusions:(1) Local fissures filled with powder rock mass material in the water-inrush zone, which led to clogging of groundwater runoff channels. The groundwater table rise up and water aggregated to a high pressure, resulting in water and stone inrush when hydrodynamic equilibrium condition was broken. (2) The circuitous pilot tunnel should be set at the downstream groundwater runoff, in order to reduce the construction risk. (3) The high discharge channel, whose bottom elevation at the end should be 6~10 m higher than the top of tunnel, should be set at upstream groundwater runoff. (4) This research result will be helpful to the analysis of hydrogeological condition and treatment of water and stone inrush of high pressure and water-rich tunnels. ©, 2015, Editorial Department of Journal of Railway Engineering Society. All right reserved.