Abstract: In order to address the problem of groundwater infiltration and inner water exosmosis induced by the hydraulic deterioration of lining joints in pressurized shield tunnels, the seepage characteristics and mechanical responses of tunnel lining and surrounding stratum under localized leakage conditions are analyzed through both numerical and analytical method based on the hydraulic aperture theory. The results show that the analytical solutions derived from the classical image method for a multi-point leakage case match well with the numerical solutions, which verifies the effectiveness of the proposed numerical model of localized leakage. There is a significant difference in the characteristics of lining-stratum interaction induced by the localized groundwater infiltration and inner water exosmosis. The former leads to a reduction of the localized pore water pressure, resulting in a more compressive interaction between lining and stratum, a reduction in the lining axial force but an increase in the bending moment and further inducing an outward deformation at the leakage region. While the latter is the opposite. The influence of multi-point localized leakage on the seepage field and lining response has a coupling effect, and a special hydraulic interaction situation where the groundwater infiltration and inner water exosmosis may co-exist when the inner water pressure approaches the stratum hydraulic head. The localized leakage behavior is largely affected by the stratum permeability coefficient. Under composite stratum conditions, the induced lining response is not significant when the localized leakage occurs in a highly permeable stratum. The seepage flow refraction phenomenon exists at the stratum interface when the leakage is in the lower stratum with low permeability, while the upper stratum with high permeability acts as either a water supplement or drainage source.

Key words: pressurized tunnel, localized leakage, inner water exosmosis, joint aperture, lining response, image method