Technological progress and innovative methods in immersed tunnel construction: a Chinese perspective

Abstract This national-level engineering-technology audit, updated to 2024, systematically examines 32 completed or under-construction immersed tunnels in China, aiming to clarify the technological evolution, innovative breakthroughs, and engineering validation of key technologies in this field. It traces the technical trajectory from early single-shell steel segments to large-scale steel-concrete-steel (S-C-S) sandwich structures, highlighting China’s pivotal advancements: field verification of domestic GINA gaskets and reversible wedge-shaped closure joints; integration of deep-cement-mixing piles with graded-gravel bedding to limit 30-year settlement to 20 mm; adoption of factory-line and hybrid prefabrication to achieve a 14 day segment production cycle; and refinement of immersion accuracy to ±50 mm via self-elevating leveling ships and Dynamic Positioning (DP)-guided installation vessels. These innovations form a validated, exportable technical package, providing critical references for global next-generation subsea corridor construction and demonstrating China’s technological leadership in marine engineering.