BDS Positioning Helps One-Thousand-Meter Installation of Tunnel’s Immersed Tubes for Shenzhen-Zhongshan Bridge

According to news from Guangdong Communication Group on January 22, the E7 tube section was completed for immersing and butt joint, a breakthrough of one-thousand-meter installation of tunnel’s immersed tubes; on the same day, the anchorage base plates on the west side of the Lingdingyang Bridge, a part of Shenzhen-Zhongshan Bridge, were constructed.

The Shenzhen-Zhongshan Bridge, 24 km in total length and 100 km/h of design speed, is a two-way 8-lane expressway constructed according to corresponding technical standards, and is planned to open to traffic in 2024. Its tunnel, which is about 6.8 km long and constructed with immersed tubes (about 5 km long), adopts the steel-shelled concrete composite structure (the largest one in the world) for the first time in China; it is the internationally widest submarine immersed tube tunnel composed of 32 tube sections and a final joint.

E7 is a standard tube section, 165*46*10.6 m in dimension and about 80,000 tons in weight. The immersing depth this time is nearly 34 m, the maximum depth since the immersed tube tunnel construction.

E7 is the first tube section placed on a natural foundation, that is, no foundation treatment is required after the excavation of the immersed tube trench; at the bottom of the tube is distributed with weathered rock formation, posing great risk of interlaid silt. “The construction team of immersed tubes monitored the siltation in real time, arranged desilting work in advance, prepared elaborate plans and comprehensively implemented all countermeasures.” so said Ning Jinjin, executive deputy chief engineer in the Project Department of Shenzhen-Zhongshan Bridge by CCCC First Harbor Engineering Company Ltd.

At 3 a.m. on January 21, the world’s first floating-transport-installation integrated vessel “Yi Hang Jin An-1” carrying E7 tube sections set sail from Guishan Niutou Island, and finally arrived at the construction site near the artificial island to the west of the Shenzhen-Zhongshan Bridge at 14 p.m. the same day, after 50-km floating across 7 waterways. At 19:30. the E7 tube section started to be immersed.

At 3 a.m. the next day, after nearly 24-h continuous operation, the seventh tube section (E7) of the immersed tube tunnel of Shenzhen-Zhongshan Bridge was smoothly immersed and butt joined. So far, a total of 1,113.5 meters of the submarine tunnel was constructed.

BDS was applied in this installation; by providing real-time 3D dynamics based on measurement tower data, the commander can understand accurately the specific position of the immersed tube on the seabed.

On August 28, 2020, BDS was applied for the first time as the principal positioning device in the project during the installation of the E3 tube section for the immersed tube tunnel of Shenzhen-Zhongshan Bridge. The successful installation of the E3 tube section proves that BDS can be effectively applied in cross-sea passage projects by virtue of its engineering-oriented accuracy and reliability.

BDS was also applied in the immersing of the E7 tube section. At 3 a.m. of the 22nd, a “deep-sea hand-in-hand” was realized after the E7 tube section and the already installed E6 tube section were precisely butt joined.

Song Shenyou, deputy director and chief engineer of Shenzhen-Zhongshan Bridge Management Center, said that, more tube sections will be immersed and installed this year as planned, and the first super-wide and variable-width tube section is hopefully immersed in August the same year.