Abstract: To address the technical challenges of underwater highway shield tunneling under complex geological conditions and highrisk construction scenarios characterized by ultra-large diameters, ultra-long distances, ultra-high water pressures, and large overburden depths, the authors systematically summarize the key technological innovations and engineering practices of the Haitai Yangtze River Tunnel in shield machine design, construction control, structural installation, and intelligent management. The main conclusions are as follows: (1) The applications of an 8.6 m-diameter monobloc heavy-duty main bearing, intelligent cutterhead tool monitoring, and multistage shield tail sealing technologies enhanced the adaptability and reliability of ultra-large cross-section shield machines for ultra-long-distance construction in ultra-high-water-pressure, highly abrasive and permeable strata; (2) Dynamic stability of the excavation face in highly permeable strata was achieved through slurry fracturing model tests and theoretical analysis of slurry membrane formation for ground stabilization; (3) Construction safety and efficiency for ultra-long-distance tunneling were ensured through the development of synchronous two-component grouting, efficient slurry circulation, and combined ventilation and cooling systems; (4) Millimeter-precision installation and process coordination were realized through industrialized construction technologies, including high-precision novel embedded joint connector (dual D-components+C-component+I-component, DDCI), integrated box-section gallery synchronous assembly, and structurally integrated fire-resistant smoke duct panels; (5) A cloud-edge-device collaborative construction system centered on remote intelligent control, intelligent welding, and digital twinning was established, promoting the intelligent and industrialized transformation of tunnel engineering.

Key words: underwater shield tunnel, super-large diameter, extra-long tunnel, slurry fracturing test, novel embedded joint connector (dual D-components+C-component+I-component, DDCI), intelligent control and management