Research and Application of Water Load and Internal Forces in Composite Linings of Subsea Tunnels

Abstract

Water loads on subsea tunnel linings are governed by the combined effects of seepage, structural deformation, and the grouting zone. However, these factors are often treated separately in existing analytical studies. In this study, an analytical model is developed for steady-state saturated seepage around a deep-buried subsea tunnel. The surrounding rock, grouting zone, primary lining, and secondary lining are represented as distinct hydraulic zones, with a constant permeability coefficient assigned to each zone. The analytical results are compared with numerical simulations and show good agreement. Parametric analyses indicate that increasing the grouting-zone thickness or decreasing its permeability reduces the water pressure behind the secondary lining and the lining stress. This effect becomes more pronounced at higher allowable drainage rates but gradually diminishes beyond a certain parameter range. Field monitoring in the Zhujiangkou Tunnel further shows a maximum relative error of 6.89% for the water pressure behind the lining, supporting the applicability of the proposed analytical method.