A Coupled Rock-Pipe Hydraulic Model for Predicting Groundwater Pressure on Tunnel Linings with Embedded Drainage Networks

In order to predict groundwater pressure on tunnel linings with embedded drainage networks, as needed in the design of tunnels under high water pressure, a coupled hydraulic model is proposed by incorporating seepage in the surrounding rocks and pressurized flow in the networks. The model is executed using the software Comsol Multiphysics and applied to analyses of a high-speed railway tunnel in China. Comparative analyses indicate that the model is more comprehensive and accurate than existing models in the literature. For rocks with low hydraulic conductivities (< 3 × 10⁻⁵ m/s), the water pressures calculated from the existing models are about the same as those from the proposed model; however, for rocks with medium to high hydraulic conductivities (> 3 × 10^–5 m/s), the existing models may err on the unsafe side by significantly underestimate the water pressures. Moreover, the more permeable the rock, the greater the underestimation of the water pressure on the lining. Meanwhile, some valuable suggestions for the embedded drainage networks are obtained through parametric analysis based on the proposed model. The proposed model is valuable for designing linings with embedded drainage networks for tunnels under high water pressure.