As the power head of the three-axis mixing pile machine—about 40 meters tall, weighing around 200 tons, and dressed in "Tiffany green"—slowly rose, the rotating drill pipe gradually decelerated and stopped. The dry dock waterproof curtain of the Shunde District Lungui Road Project (Hengyi Road–Hengwu Road Section), constructed by the Shunde Lungui Road Project Department of CCCC First Harbor Engineering Co., Ltd., was successfully closed.
"This project is the first inland river immersed tube tunnel project of CCCC First Harbor Engineering Co., Ltd. It has a tight schedule, high technical difficulty, and stringent environmental protection requirements. It is currently the inland river concrete immersed tube tunnel with the largest single-span and the largest cross-section in China," said project manager Xu Bo. The Shunde District Lungui Road Project (Hengyi Road–Hengwu Road Section) adopts the Class I highway construction standard and runs overall north-south, crossing the Tanzhou Waterway via a two-way, eight-lane immersed tube tunnel. The dry dock foundation pit has an excavation depth of 12.85 meters and a cumulative excavation volume expected to reach 499,740 cubic meters. With extremely high safety requirements, it is a Class I deep foundation pit project.

It is reported that within the excavation depth of the dry dock, the works must pass through six engineering geological strata and one engineering geological sub-layer, and the geological conditions are complex. The north side of the dry dock is only 50 meters from the Tanzhou Waterway. The soil in the construction area has high water content and strong permeability, which greatly affects the pile-forming quality of the concrete mixing piles. In addition, the project red line is only 50 meters away from the residential area. Therefore, the key difficulties of the project include not only solving the water-stopping problem during dry dock excavation, but also ensuring the construction safety of the deep foundation pit and avoiding noise disturbance to residents.

To overcome these difficulties, the project department adopted a scheme of waterproof curtains on three sides plus a temporary flood dike for the dry dock area, and innovatively applied the three-axis cement mixing pile construction technology for geological conditions of water-adjacent high-permeability strata, aiming to solve the problems of poor pile-forming performance of cement-soil mixing piles used for waterproof curtains in high-permeability strata and soft foundation reinforcement.

Since entering the fourth quarter, the project department has organized meticulously and arranged scientifically, charging toward the annual production target and raising the banner of project construction like the wind. By applying the three-axis cement mixing pile construction technology for geological conditions of water-adjacent high-permeability strata, the construction period was greatly shortened and construction costs were saved. Ultimately, the closure of the dry dock waterproof curtain was successfully achieved, laying a solid foundation for realizing the goal of secondary excavation of the dry dock by the end of the year and providing favorable conditions for subsequent immersed tube prefabrication.