Case study on the uplift of tunnel segments due to grouting layer deterioration during shield tunnel operation in karst fissure development strata

This study investigates the causes and impacts of shield tunnel segment uplift, particularly in karst fissure strata, where groundwater changes and geological conditions are often overlooked. Through a case study and 3D finite difference modeling, it was found that deterioration of the grouting layer, exacerbated by train vibrations and groundwater erosion, forms cavities that reduce surrounding rock confinement, leading to segment uplift and elliptical deformation. This deformation increases bending moments, decreases axial force, and worsens joint misalignment and leakage. The research highlights the critical role of grouting layer integrity in preventing uplift and provides practical insights for design, construction, and maintenance to mitigate structural risks in tunnel engineering. • Segment uplift in shield tunnels: Causal links to leakage & damage analyzed during operational phases. • Elliptical deformation from uplift triggers joint opening and misalignment. • Groundwater-grout void interactions drive uplift, opening, and misalignment in tunnel segments. • Grout layer deterioration (vibrations/erosion) directly drives major tunnel damage risks.