Following the precise final sinking of the world's largest in-construction water caisson at the end of January, the caisson of Pier 6 of the Changtai Yangtze River Bridge has smoothly entered the base sealing operation stage, laying the foundation for the next phase of “water-to-land” construction of the main tower pier.

On February 19, the caisson of the main tower pier of Pier 6 of the Changtai Yangtze River Bridge——the world's largest underwater steel caisson foundation, constructed by China Railway Major Bridge Engineering Group——began base sealing operations, pouring 47,000 cubic meters of underwater C30 concrete. Base sealing of the caisson is an important process conversion for the main pier construction of the Changtai Bridge from water to land. The caisson of the main tower pier of Pier 6 adopts zoned base sealing, divided into six zones, with a sealing thickness of 11.5m. The zones are sealed with crushed stone and arranged in an “H” shape.

After 2 days and 2 nights of uninterrupted construction, Zone III of the caisson was the first to complete the pouring of 9,000 cubic meters of concrete. On February 22, workers organized the base sealing construction platform and made preparations for base sealing in the next zone. Wei Xiaoning, on-site technical director for Pier 6 of the Changtai Yangtze River Bridge Project Department of China Railway Major Bridge Engineering Group, introduced: “During the Spring Festival, more than 600 employees of the project department gave up family reunions and celebrated the festival on site, making preparations for base sealing in advance. During the base sealing construction, we adopted a two-shift mode, pouring concrete 24 hours a day without interruption.”

Due to the large volume of caisson base sealing, in order to ensure the integrity of the sealing concrete and project quality, on the basis of the original water-based mixing station, the project department also deployed a water-based concrete working boat and an onshore mixing station to ensure uninterrupted concrete supply. Base sealing in the next zone is expected to be carried out in a week, and the entire base sealing operation is expected to be completed before the end of April. Zou Zhenlei, deputy secretary of the Party Working Committee of the Changtai Yangtze River Bridge Project Department of China Railway Major Bridge Engineering Group, stated: “After the caisson base sealing is completed, we will shift from waterway construction to land-based construction. The most difficult underwater construction parts have all been overcome, which will lay a solid foundation for the subsequent construction of the pile cap and pier body.”

It is reported that the Changtai Yangtze River Bridge is the first river crossing in the Yangtze River to integrate expressway, intercity railway, and first-class highway as a “three-in-one” passage, with a total length of about 37.3 kilometers. The upper deck is a two-way six-lane expressway, and the lower deck is a double-track intercity railway and a two-way four-lane first-class highway. Its main navigation channel bridge is a double-deck steel truss cable-stayed bridge with a main span of 1,176 meters, and the dedicated navigation channel bridge is a double-deck steel truss arch bridge with a main span of 388 meters, both ranking first in the world among bridges of the same type.