On November 29, the ultra-wide, variable-width tube section E29 of the Shenzhen-Zhongshan Link immersed tunnel completed its connection. A joint breakthrough measurement by three parties confirmed that the connection accuracy of the tube section meets acceptance evaluation standards.

Tube section E29 of the Shenzhen-Zhongshan Link immersed tunnel undergoing floating transport

The Shenzhen-Zhongshan Link subsea tunnel is about 6,800 meters long, with an immersed tube section of about 5,000 meters, consisting of 32 tube sections and one final joint. It is the world's widest steel-shell concrete subsea immersed tunnel.
Tube section E29 was constructed by the S08 contract section of the Shenzhen-Zhongshan Link project under the consortium of Poly Changda and the Guangzhou Salvage Bureau. It is the fourth ultra-wide variable-width non-standard tube section at the eastern end of the Shenzhen-Zhongshan Link immersed tunnel, about 123.8 meters long, with a maximum width of about 49.75 meters and a weight of about 64,000 tonnes after casting.
In the early hours of November 28, towed by nine tugboats with a total horsepower of over 44,000 under the Guangzhou Salvage Bureau, tube section E29 set off from the Nansha Longxue dock basin in Guangzhou for the tunnel site. At 15:00 on November 28, tube section E29 crossed the busiest Lingding Channel and Fanshi Waterway at the Pearl River Estuary, successfully arrived at the tunnel site, and carried out mooring, winching and shifting operations.

Tube section E29 of the Shenzhen-Zhongshan Link immersed tunnel sets sail from Nansha

To ensure the connection accuracy of the immersed tube, the construction team of the Guangzhou Salvage Bureau used an auxiliary decision-making system for immersed tunnel construction jointly developed with the Tianjin Research Institute for Water Transport Engineering.
"This system integrates the functions of various high-precision devices such as total stations and attitude sensors. Through rigorous calculation by the software system, it can display the immersed tube conditions in real time in 2D and 3D forms, achieving full-process navigation, positioning and monitoring of tube section connection, and effectively solving the measurement and control challenges of irregular ultra-wide variable-width tube sections," introduced Sun Shipeng, deputy production manager of the S08 contract section of the Shenzhen-Zhongshan Link under the Guangzhou Salvage Bureau.
At 14:30 on November 29, after nearly four hours of fine adjustment, immersion, pulling and connection, and hydraulic pressure joining, tube section E29 completed its connection and installation at a depth of about 25 meters underwater.
At 20:30, a joint breakthrough measurement by three parties confirmed that the connection accuracy of the tube section meets acceptance evaluation standards, and the construction team once again completed the immersed tube installation and connection with millimeter-level precision.

Tube section E29 of the Shenzhen-Zhongshan Link immersed tunnel crosses the busy Pearl River channel toward the Shenzhen-side tunnel site

Tube section E29 involved 23,000 cubic meters of concrete and officially began prefabrication in May this year. "To ensure efficient and high-quality completion of tube section prefabrication, we broke through the previous 'interval-based' alternating construction method and added an additional steel-shell tube section assembly station in the dock. That is, while casting one tube section, the steel-shell assembly of the next tube section is carried out simultaneously, achieving assembly-line production and improving construction efficiency," introduced Su Zongxian, chief engineer of the S08 contract section of the Shenzhen-Zhongshan Link under Poly Changda.
Ultimately, the construction team completed the casting and prefabrication of tube section E29 as planned and shifted it out of the dock to the storage area, laying a solid foundation for this immersed tube installation.

Casting site of tube section E29

At present, construction of the Shenzhen-Zhongshan Link immersed tunnel is progressing steadily. A total of 18 tube sections have been successfully installed, including 4 on the east side and 14 on the west side, and the immersed tunnel length has reached 2,764 meters.