The Chepo South Tunnel. [Photo/WeChat account: tianhefabu]

The Chepo South Tunnel, which has recently started operation in Tianhe district, is the first immersed tube tunnel in an urban inland river on the Chinese mainland to achieve zero water infiltration.

The 2.07-kilometer tunnel has a 492-meter-long immersed section, and is a strategic development corridor going from Guangzhou International Financial City directly to Pazhou.

"The key to creating a zero-infiltration immersed tube is to have complete control over cracking concrete," said Yu Fang, the person in charge of the project's concrete technical team. 

After 426 days and hundreds of comparative tests, Yu led the technical team to develop an exclusive formula for the Chepo South Tunnel. The revolutionary formula involves a concrete mix with low heat generation, a low shrinkage rate, and high crack resistance.

The Chepo South Tunnel project teams test the immersed tube for infiltration. [Photo/WeChat account: tianhefabu]

In addition, any immersed tube must be at a suitable freeboard depth to maintain stability when floating, which is dependent on the tight control of the tube's concrete density deviation to within 20 kilograms per cubic meter. The technical team achieved a density deviation of within 10kg kg/m³ for this project.

The project construction team, in conjunction with the technical team, also introduced information technology to help realize the intelligent casting of the immersed tube during the concrete pouring process.