ABSTRACT
Leakage defects at segmental joints have laid a significant challenge to the long-term safety of shield tunnels. It can be induced by both joint deformation and rubber degradation, leading to further ground consolidation and continuous development of structural deformation. A FEM analysis was conducted to study the influence of long-term localised leakage on the soil-tunnel interaction and structural behaviour of tunnel lining. A comprehensive algorithm was incorporated into the model to elucidate the hydro-mechanical coupling behaviour of the gasketed joint, showcasing a waterproof stage followed by sealant failure. The cubic law was utilised to characterise the leakage behaviour through gaskets, and the realistic effective hydraulic aperture and hydraulic gradient along the gasket interface were considered. The results indicate that for the background project, the gasketed joint can endure the external groundwater pressure for 40 years when the initial opening of the joint is at maximum tolerance. The negative bending mode of the joint causes additional hydraulic deterioration and accelerates the waterproof failure, indicating a significant hydro-mechanical coupling behaviour. The localised leakage also intensifies the structural response of the whole lining, as evidenced by increases in both bending moment and axial force, particularly at the leakage side. After 100-year operation, the tunnel crown and invert settlement can reach 36.5 and 30.4 mm, respectively, due to the continuous consolidation of the strata, indicating a noticeable ovalisation trend of the lining
