As the Xiangjiang Changsha to Chenglingji Class I Waterway Construction Project's Xiangjiang Changsha Comprehensive Hub Third-Line Ship Lock Project advances vigorously, on December 19, reporters learned from Hunan Provincial Water Transport Construction Investment Group Co., Ltd. that a new breakthrough has been achieved in the design and construction of the foundation pit cofferdam, a key difficulty of the project.
Hunan Province's First 3,000-Ton-Class Waterway Construction Project
The Xiangjiang Changsha to Chenglingji Class I Waterway Construction Project is a key water transport construction project in the 14th Five-Year Plan of the Ministry of Transport and Hunan Province, and also Hunan Province's first 3,000-ton-class waterway construction project. With a total investment of 3.203 billion yuan, the project is invested by Hunan Provincial Water Transport Construction Investment Group Co., Ltd. and constructed by CCCC Fourth Harbor Engineering Co., Ltd., with a construction period of 36 months. The construction content includes the new Xiangjiang Changsha Comprehensive Hub Third-Line Ship Lock, waterway dredging, bridge anti-collision facilities, and building construction and other supporting works. The project is expected to be fully operational in 2027.
The project's construction content covers large ship locks, waterway dredging, bridge anti-collision facilities, and building construction and other supporting works. Its controlling project, the Xiangjiang Changsha Comprehensive Hub Sanxiang Ship Lock, is characterized by a large project volume, complex boundary conditions, and construction in close proximity to existing bridges, buildings, embankments, and other structures. Among these, the construction of more than 1,000 rock-socketed support piles and anchor cables has become the key to completing the project on schedule and ensuring safe implementation.
It is reported that the deepest part of the foundation pit of the Xiangjiang Changsha Comprehensive Hub Third-Line Ship Lock reaches 35.4 meters, a depth extremely rare among similar domestic projects, placing extremely high demands on the design and construction of the foundation pit support system. At the same time, the ship lock is adjacent to existing bridges, buildings, embankments, and other structures, with narrow construction space, water on multiple sides, and strict requirements for protecting bridge piers, further increasing construction difficulty.
Rare Foundation Pit Depth, Innovative Solutions Overcome Difficulties
Facing this challenge, the project construction department of CCCC Fourth Harbor Engineering Bureau tackled the difficulties head-on and adopted a series of innovative measures. In response to the ultra-deep excavation support challenge around existing structures, multiple support methods such as rock-socketed support piles and anchor cables were adopted to build a multi-level, three-dimensional pile-anchor support system. These support piles and anchor cables extend deep into the rock strata, cooperate closely with one another, and bear loads jointly, firmly safeguarding the stability of the ship lock foundation pit like a steel Great Wall and laying a solid foundation for subsequent ship lock construction.
At the same time, in response to the difficulties faced by the cofferdam in the dam-crest bridge section, including water on multiple sides, strict bridge pier protection requirements, and narrow construction space, the design unit creatively proposed a "permanent-temporary combined design scheme using the navigation wall structure as the cofferdam" and, for the first time, adopted "double-row piles + inclined piles" and "multi-row piles" support methods, ingeniously avoiding the squeezing and encroachment on bridge piers caused by traditional earth-rock cofferdams and fundamentally eliminating the risk of cofferdam squeezing and collapse.
In terms of construction, the project construction department adopted efficient construction technology for ultra-deep pile-anchor support structures, achieving efficient construction of foundation pit support; through automated equipment, monitoring of groundwater levels, anchor cable internal forces, and other parameters was carried out, ensuring the safety and accuracy of construction. After the project is completed, it will greatly enhance the navigation capacity and transport efficiency of the Xiangjiang waterway, promote rapid regional economic development, and at the same time provide valuable experience for waterway construction in Hunan Province and even the whole country.
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