Water infiltration in drained circular tunnels: an analytical solution and its simplification

Underwater tunnels are often subject to groundwater infiltration, which can pose risks both to the tunnel's safety and the groundwater environment. Analytical solutions are commonly used to estimate the rate of water infiltration in tunnels. However, there is a lack of research on the analytical solution of tunnels with drainage systems. The aim of this study was to investigate groundwater seepage in tunnels with circumferentially arranged drainage pipes. The analytical formula for estimating the inflow rate takes into account the seepage processes in the ground, primary lining and geotextile. The accuracy of the analytical solution is confirmed by comparing it with numerical results. The analytical solution's general form is simplified for tunnels with varying permeabilities of the surrounding strata and geotextiles, and a query chart is created to facilitate engineering applications. The research findings can serve as a theoretical basis and reference for the establishment of relevant specifications and the design of tunnel drainage systems.