Simulation of the self-potential response during the water inrush of tunnel beneath surface water:a case study of Shijingshan tunnel in Zhuhai
Water inrush is one of the most serious geological hazards during tunnel excavation in complex geological areas.If there was the surface water,the excavation of tunnel could cause the water inrush when crossing the fracture zone.The water inrush in tunnel endangers the safety of workers and slows the progress of construction.In this paper,a numerical model was used to simulate the process of water inrush and self-potential response in the Shijingshan tunnel at Zhuhai City,based on the fundamental theory of the self-potential method.The distribution characteristics of the self-potential field at the tunnel's longitudinal and transverse sections under various working conditions are explored.The results show that the self-potential increases along the path of groundwater flow and reaches the maximum value of 105.3 mV at the tunnel face.The self-potential signals are proportional to the groundwater flow velocity as well as the flow rate.The self-potential signals in the tunnel's longitudinal and transverse sections are inversely proportional to the water head.This study demonstrates that the self-potential response could effectively identify changes in the groundwater flow field induced by tunnel excavation,which means it could be used as an effective early warning method for the water inrush of tunnel.
TunnelWater inrushSelf-potential responseGroundwater flow fieldSurface water
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