Water Hazard Characteristics of PiShuangAo Karst Tunnel

An Chen, Yi Zhou, Lu Chen

Abstract


To study the water hazard characteristics of PiShuangAo karst operating tunnel, engineering geological mapping and survey, hydrogeological mapping and survey, karst customised research, tunnel water hazard investigation, theoretical calculation and analysis are used. The results show that the karst in tunnel hill developed well. There are twenty-five round or oval karst funnels and karst collapses. The maximum diameter of collapse is 35m and the deepest depth is 25m. The deepest sinkholes reach the top of the tunnel. There is no perennial water body on the surface of tunnel hill. There are 44 gushing water places in PiShuangAo tunnel during rainy season, which are water pouring and water inrush mainly. But there is no gushing water during dry season in the tunnel. The water source of tunnel water hazard is rainfall, the gushing water channels are sinkholes and karst caves. The calculation results show the rainfall intensity are 3.8mm/h、6.1 mm/h、8.3 mm/h、 12.0 mm/h respectively, the rainfall time that lead to the gushing water exceeds the drainage capacity of the gutters are 2.0h 、1.3h、1.0h、0.7h respectively. And when the rainfall intensity is 33.3mm/h, the rainfall time is just 15min. The tunnel gushing water causes a lot of water, mud and sands flowing on the road that endanger traffic safety, and even leads to traffic disruption.


Keywords


karst; tunnel; water hazard; characteristic

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