Journal of Engineering Research and Reports

High-pressure water-conveyance shield tunnels operate at the intersection of pressurised hydraulic infrastructure, discontinuous segmental structures and deformable ground. Leakage can be a consequence of joint opening, cracking or interface separation, yet it may also alter pore-water pressure, effective ground support, structural forces and the subsequent progression of damage. This critical narrative review evaluates the reciprocal relationship between leakage and mechanical performance, distinguishing outward loss of conveyed water from inward groundwater ingress and from redistribution of pressure within composite linings. Peer-reviewed experimental, field, analytical and numerical investigations were evaluated thematically, with particular attention to evidence directly obtained from pressurised water-conveyance tunnels and to transferability from underwater transport and drainage tunnels. The synthesis identifies joint deformation and gasket contact conditions as relatively well-supported immediate controls of watertightness, whereas time-dependent soil–lining feedback and leakage-induced loss of global capacity remain less conclusively validated for internally pressurised tunnels. Full-scale tests indicate that internal pressure can reduce compressive ring forces, promote joint opening and redistribute loads among concrete segments, inner linings, steel shells and surrounding ground. Composite-lining experiments also show that cracking of self-compacting or reinforced concrete does not necessarily constitute complete hydraulic failure, provided alternative barriers remain intact. Conversely, the benefits of double gaskets, prestressing and fibre reinforcement depend on deformation compatibility and failure mode; improved strength alone cannot establish watertightness. An integrated performance framework is advanced in which hydraulic gradient, leakage pathway, joint and lining deformation, permeability evolution, external restraint and time-dependent degradation are assessed together. Priority needs are bidirectional pressure testing, repeated-load and ageing validation, monitoring capable of identifying leakage direction and location, and independently calibrated three-dimensional hydro-mechanical models. Design and maintenance should use explicit serviceability and ultimate limit states rather than treating a single leakage threshold as a universal measure of structural safety.