Abstract:
To address damages of lining structures of deep-buried tunnels due to high underground water pressure, and ecological environmental issues such as ground subsidence and vegetation damages caused by excessive drainage in fully drained tunnels, we propose a novel tunnel drainage design idea that incorporates controlled water discharge through drainage valves.This design effectively reduces the groundwater pressure behind the lining and controls the amount of groundwater discharged, thereby minimizing the impact of tunnel drainage on the groundwater environment, embodying a combined concept of prevention and control in groundwater management.Based on the proposed design for deeply buried tunnels, a theoretical solution of three-dimensional seepage was presented considering the effect of drainage valves which enable adjusting discharge volume feasible.By modulating the spacing and pressure of these valves, it is possible to keep tunnel drainage and the water pressure behind the lining within acceptable limits.The validity of this theoretical solution is corroborated through comparative analysis with numerical calculations, demonstrating high consistency.Furthermore, a parameter analysis was conducted to explore influences of groundwater level, permeability coefficient, valve spacing, and valve pressure, so a corresponding tunnel drainage and water resistant design was proposed.This paper presents relevant engineering case studies, offering practical guidance for design of this new type of tunnels equipped with drainage valves.