On January 22, through 24 hours of undocking, floating transporting, mooring, and immersing, the E7 Pipe section of the immersed tube tunnel section of Shenzhen-Zhongshan Channel has been finally millimeter-level accurately connected with the installed pipe sections. Up to now, the total length of the immersed tunnel which has been completed is 1,113.5 meters, achieving the “Kilometer” breakthrough and ushering in a “good start” in 2021 for the construction of the Shenzhen-Zhongshan Channel Project.
The E7 Pipe
section of the immersed tube tunnel is under sinking and docking. (Shot by Lu
Zhihua)
The E7 which is installed is a standard pipe section, 165 meters long, 46 meters wide, 10.6 meters high, and weighed about 80,000 tons. "After the E7 has been installed, the elevation of the bottom of its headend is about -31 meters, and the bottom of its tail end, 34 meters, breaking through the record concerning the depth since the commencement of the immersed tunnel." Ning Jinjin, Executive Deputy Chief Engineer of Shenzhen-Zhongshan Channel Project Office of CCCC First Harbor Engineering Co. Ltd., said that the depth of the sinking location is approaching 34 meters, which reaches the deepest since the execution of the immersed tube tunnel.
The worldwide first integrated ship of floating transportation-installation for immersed tube, is towing E7section towards the location for sinking. (Shot by Zhang Zizheng)
At 3:00 am on January 22, the E7 section and E6 completed their connection under hydraulic pressure, realizing a subsea “Joining Hands”. With the smooth installation of the E7 section, the total length of the immersed tunnel which has been constructed reaches 1113.5 meters, achieving the “Kilometer” breakthrough and ushering in a “good start” in 2021 for the construction of the Shenzhen-Zhongshan Channel Project. According to the schedule, the project will complete the installation of 8 immersed pipes this year, and the total length of the tunnel constructed will exceed 2,200 meters.
The workers are working on the top of the tube section to be immersed under sea
Successful installation of the first tube section installed on natural foundation
“The E7 section is the first of its kind installed on natural foundation, and the foundation treatment is to pave a one-meter-thick gravel layer.” said Ning Jinjin. For the six tube sections which had been sunk before, the foundation treatment was to lay gravel layer and a rubble compacted layer. Due to the good geological conditions in the sea area where the E7 section is located, only gravel layer is used for the foundation treatment, which necessitates higher requirements for dredging. In view of the risk of abnormal foundation caused by silting, the construction team real-time observed the silting situation, arranged the cleaning work reasonably, and finally successful installed the first section installed on natural foundation.
It is informed that on August 28, last year, during the installation process of E3 section of the immerged tube tunnel, it was the first time for the project to install the section mainly with assistance of China's self-developed BeiDou Navigation Satellite System (BDS). The BDS once again played a huge role in the immersion and installation of E7 section. The three-dimensional dynamics of the immersed tube section can be calculated in real time based on the monitoring date from the monitoring tower, which helps the commander to accurately take control of the specific position of the immersed section under the sea.
