Long-Distance Pipe Jacking Completed in Nantong, China
As the largest water plant currently under construction in Nantong, China, the Ligang Water Plant will deliver a total water supply capacity of 1.2 million cubic meters per day upon completion, providing high-quality Yangtze River raw water for millions of residents in Nantong’s main urban area and western regions. Serving as the core section of the entire project, the water intake pipe jacking works adopted two 2.6-m diameter pipe jacking machines independently developed by CREG to construct two water intake pipelines extending from onshore areas to the center of the Yangtze River.
Launching from the No. 2 jacking shaft, the equipment completed full-length, one-time continuous tunneling beneath the Yangtze River bed, traversing the Yangtze River flood levee, river shoals and dedicated navigation channel successively. The construction faced extreme technical challenges, including deep burial, high water and soil pressure, and long-distance jacking.
Conventional large-diameter steel pipe jacking normally limits single jacking length within 2,000 m. In this project, the maximum single jacking distance reached 3,214.96 m, bringing prominent technical difficulties including long-distance slurry transportation, continuous jacking force loss and high-precision axis deviation correction. Located 43 m below the riverbed, the pipelines endured enormous stratum pressure. The local soft silty sand formation is highly susceptible to water inrush and ground settlement, requiring extremely high standards for pipeline tightness and tunneling stability. Throughout the crossing of the Yangtze River navigation channel and first-class flood control levee, the construction achieved zero damage to flood control structures and zero impact on river shipping operations.
To overcome these complex geological and technical barriers, CREG collaborated closely with design and construction teams to carry out targeted technological innovations in equipment development and construction techniques. The project team achieved breakthroughs in high-strength wear-resistance technologies and real-time wear detection technologies for small-diameter cutterheads, and developed a dedicated sealing system adaptable to ultra-high underwater pressure conditions. With specialized drag-reducing slurry and customized grouting solutions, the overall operational reliability and jacking efficiency of the equipment for ultra-long-distance tunneling were significantly enhanced.
Officially initiated on Nov. 3, 2025, the project achieved successful breakthrough of both pipeline drives on June 24, 2026. The maximum monthly tunneling progress reached 540 m, with the left line jacking 3,214.96 m (10,547.769 ft) and the right line 3,208 m (10524.93 ft), establishing a new global record for the longest single jacking distance in pipe jacking engineering.
The successful completion of the project represents a major technological leap in global long-distance underwater pipe jacking construction. It has established a fully independent and domestically developed technical system integrating complete sets of ultra-long underwater pipe jacking equipment and mature construction methodologies, providing a standardized and replicable reference for large-scale cross-river and cross-sea underground pipeline projects involving water intake, sewage disposal, and oil and gas transmission.
As a core foundational component of the Ligang Water Plant project, the underwater pipe jacking construction provides a strong guarantee for the high-quality and efficient progress of the overall engineering works. Upon full operation, the Ligang Water Plant will empower Nantong to build a more complete, resilient and efficient regional water supply system, substantially upgrade the city’s water supply capacity and emergency water security reserve, and provide solid infrastructure support for the city’s long-term high-quality development.
