At 10 a.m. on July 5, 2026, at a depth of 43 meters beneath the Yangtze River, a "water intake umbilical cord" lying across the riverbed officially entered the annals of history. The water intake pipe jacking project of China's Nantong Ligang Water Plant achieved a single jacking length of 3,214.96 meters, earning the Guinness World Record for the "Longest Pipe Jacking" and setting a new benchmark in underwater infrastructure. This super project, hailed by the industry as the "World's Top Pipe Jacking," marks China's ultra-long-distance water pipe jacking technology as reaching an internationally leading level.

Dual Lines Parallel for 234 Days, Millimeter-Level Precision Breakthrough

Located on the Yangtze River shoal in Wujie Town, Tongzhou District, Nantong City, Zhejiang Province, the Ligang Water Plant is a key project for optimizing the city's water supply layout and strengthening livelihood security. With a planned total daily water supply capacity of 1.2 million cubic meters, it will become the largest water plant in Nantong upon completion.

The project employs dual DN2600 ultra-large-diameter steel pipe jacking, invested and constructed by Nantong Water Group, with joint construction by Shanghai Highway and Bridge (Group) Co., Ltd. and China Railway Engineering Equipment Group Co., Ltd. Starting from the river crossing launch on November 3, 2025, after 234 consecutive days of intensive work, the pipe jacking equipment smoothly traversed key points such as the Yangtze River shoal and dedicated navigation channels. Ultimately, the left line was jacked 3,214 meters and the right line 3,208 meters, with the dual lines precisely "meeting" at the river center, achieving millimeter-level breakthrough.

Four Core Innovations Tackle World-Class Challenges

Ultra-long-distance steel pipe jacking beneath the Yangtze Riverbed is a world-class engineering challenge. Nantong is situated in the alluvial plain of the lower Yangtze River, a typical water-rich soft soil stratum with high moisture content and strong permeability. The construction pipes needed to be buried 43 meters deep beneath the riverbed, compounded by over 40 meters of ultra-high water pressure, a mixed soft-hard composite stratum, and the dual constraints of Yangtze River navigation and ecological protection. The project team overcame a series of industry technical bottlenecks through four core technological innovations:

1. China's Customized Domestic Pipe Jacking Equipment

The project relied on China's customized domestic pipe jacking equipment and a full-process intelligent monitoring and control system, collaborating with all participating parties for specialized technical research. The pipe materials were exclusively supplied by Zhejiang Jinzhou Pipe Industry Co., Ltd., which also deeply participated in the construction, selecting high-rigidity thick-walled pipes combined with fully automatic intelligent welding processes to precisely control pipe roundness and dimensional accuracy. Both the inner and outer surfaces of the pipes were treated with specially customized epoxy powder and professional coating processes, ensuring a smooth inner wall to reduce water transmission loss, and outstanding outer wall corrosion and water-soil erosion resistance, complemented by optimized joint sealing structures for comprehensive leak prevention.

2. Composite Reinforcement Process in the Launch Area

To ensure smooth project implementation, the team innovatively adopted a composite process of "MJS reinforcement + freezing method" in the launch area, effectively solving stability challenges during launch and reception in water-rich soft soil strata.

3. Full-Process Digital Intelligent Control

The project team implemented full digital control, relying on a high-precision guidance measurement system for 24-hour uninterrupted monitoring, real-time tracking of machine head posture, pipe axis, and water-soil pressure changes, and dynamically adjusting excavation parameters. By precisely controlling the jacking axis, jacking force, and water-soil pressure, they effectively resolved technical bottlenecks such as high resistance in long-distance jacking and difficulty in deviation control.

4. Multi-Stage Intermediate Jacking and Friction-Reducing Mud System

By improving the mud-water balance construction process, optimizing polymer mud wall protection technology, and scientifically deploying multi-stage intermediate jacking devices, the project team effectively solved the challenge of high resistance in long-distance excavation. The two pipe jacking lines were spaced only 6.51 meters apart, making them susceptible to mutual disturbance during excavation, imposing extreme standards on pipe material comprehensive performance. The development of high-performance pipe jacking equipment and specialized friction-reducing mud successfully addressed this technical bottleneck.

From "World Record" to "Technical Paradigm"

The significance of this world record extends far beyond a Guinness title.

Breaking through ultra-long-distance underwater pipe jacking technical barriers. The project overcame key technical barriers in long-distance riverbed pipe jacking, accumulating mature construction experience under the unique hydrological and geological conditions of the Yangtze River. The complete set of technical solutions and construction experience formed by the project provides a replicable and scalable practical model for similar cross-river, water-related, and ultra-long underwater pipe jacking projects both domestically and internationally.

Promoting localization of large-diameter steel pipe jacking equipment and materials. From customized domestic pipe jacking equipment to high-rigidity thick-walled pipes, from fully automatic intelligent welding processes to specially customized epoxy powder coatings, the project's success demonstrates China's complete autonomous equipment and material supply capabilities in the field of large-diameter underwater pipe jacking.

Providing new solutions for urban water supply infrastructure. Traditional cross-river water intake often uses submerged pipes or open-cut methods, with long construction periods and significant environmental impact. Ultra-long-distance underwater pipe jacking technology enables precise water intake deep beneath the riverbed without disrupting river navigation or disturbing the aquatic ecosystem. This technical path offers a new option for water intake projects in many riverside cities across China.

From Nantong to All of China and the World

The Ligang Water Plant is expected to be fully operational by 2027. By then, this "water intake umbilical cord" lying across the riverbed will form a new regional water supply pattern, connecting north and south with the existing three major water plants—Chonghai, Langshan, and Honggang—complementing each other. The water supply coverage will extend to northern Chongchuan, northern Tongzhou, Haimen, Qidong, Rudong, and Tongzhou Bay, also covering Rugao, Hai'an, and Dongtai in Yancheng.

Leveraging the effectiveness of the Yangtze River protection initiative, the water quality in the Nantong section of the Yangtze River has stabilized at Class II standards. The water intake head is located at the river center, drawing the most stable mid-to-low-level water. This "water intake umbilical cord" will bring higher-quality, cleaner Yangtze River water to a wider area.

More profoundly, the complete set of technical solutions accumulated from the Ligang Water Plant pipe jacking project can serve as a practical reference model for similar cross-water ultra-long pipe jacking projects worldwide. Whether for large city water source switching, cross-sea water diversion projects, or submarine pipeline laying, this "Chinese solution" has broad prospects for promotion and application.