Experimental investigation of erosion damage and bearing performance of 3D-modeled high-precision segment models under salt-load coupling effects

This study investigates the damage characteristics and mechanical performance of shield tunnel segments subjected to external construction loads during long-term service in environments with high soil-water pressure, strong salt erosion, and weak stray currents. Scaled physical model tests were conducted using 3D printing technology to accurately reproduce segment structural features and analyze segment performance under coupled environmental and loading conditions. First, the tunnel segment specimens were subjected to saltwater erosion for 120 days before applying external loads to simulate construction-induced disturbances. A saline water circulation system, corrosion expansion strain ring, and saltwater infiltration diaphragm structure were developed to accurately simulate groundwater erosion and monitor steel corrosion expansion. Additionally, in-depth parametric analysis was conducted using numerical simulation. Both experimental and numerical results revealed that steel corrosion induced circumferential cracks, while load disturbances created longitudinal cracks in the segments. Circumferential cracks distributed corrosion damage more evenly across the segment, resulting in less overall structural damage, while the longitudinal cracks caused by combined corrosion and loading showed more concentrated damage zones with greater structural impact. Segments with single-side rebar corrosion retained partial load-bearing capacity, whereas segments with double-side corrosion showed complete structural failure. These findings suggest that after long-term service, external construction disturbances can induce numerous structural cracks in the linings of metro tunnels, significantly reducing the designed service life.