【Domestic News】Completion of “World-class Challenging Project”-West Line of Shantou Bay Tunnel Opens a New Chapter of Underwater Tunnel Construction in China
On August 7th, 2020, with the strong support of the National "863" Plan, the west line of Shantou Bay Tunnel was completed. The super-large diameter TBM tunnel, which is invested by CITIC Group, designed and constructed by China Railway Tunnel Group. It is an important milestone in the construction of Shantou Bay Tunnel after the completion of the east line on May 16, marking the successful completion of the whole Shantou Bay Tunnel, realizing the century-old dream of Chao People to across the Bay, and opening a new chapter of the underwater tunnel construction in China.
Shantou Bay tunnel is located between the Haiwan bridge and Que shi bridge, which is starting from the intersection of Tianshan South Road and Jinsha East Road, Beian Longhu district of Shantou city, then underpassing Tianshan South Road, Zhongshan East Road, Huaqiao Park and Suai Gulf, and going up the ground to the west of diving gym 200 meters away in the south bank of Shantou city, and ending at the entrance of Hutoushan tunnel, and connected with the planed Anhai road.
The total length of tunnel is 6,680 meters and the subsea tunnel is 3,407 meters long, designed to be two-way six-lane with design speed of 60kms per hour. Two super large diameter TBMs are applied to subsea tunnel construction with diameters of 15.01 meters and 15.03 meters respectively.
The diameter of 15.03m of super large TBM jointly designed by CRTG, CREG and CITICHMC, which was under construction of boulder section, bedrock, 8 magnitude earthquake area and other prohibited areas. It has taken 660 days to complete the 3,047 meters-long subsea tunnel successfully.
The Equipment integrated with five innovative technologies, including ultra-high pressure power system, atmospheric transfer technology, telescopic oscillating driving technology, and high intelligence. The new technologies not only minimized the impact on surrounding environment, well controlled the ground subsidence, but also created safe efficient worksite. It exerted an great influence on the construction of subsea tunnel and can be called as “the pillars of a great power”.
Shantou Bay Tunnel is not only the largest ocean-crossing tunnel in China, and but also the first subsea tunnel which was built in 8 magnitude earthquake area. The degree of comprehensive difficulty is the highest of its kind summarizing as “Big” “Shallow” “High” “Hard” and “Risk”. "Big" means that the diameter of the TBM is up to 15.03 meters, which is super large diameter. "High" means that the project located in high earthquake-intensity area, "Hard" means that the rock strength is up to 216MPa. "Shallow" means that the overburden of soil on the TBM is only 8.2 meters from the starting point of the tunnel. "Risk" means that the tunnel is located in unstable stratum, with extremely poor stability of submarine mollisol, it will result in great difficulty in construction and high risk in safety, especially the TBM should bore three sections of protruding bedrock with a length of up to 182 meters.
During the construction, CITIC and CRTG set up an on-site National Key Laboratory of TBM technology on the basis of Shantou Bay Tunnel Project. Around 50 seminars have been held, and inviting experts to discuss relevant issues. Finally, the double tunnels have been successfully completed.
Shantou Bay Tunnel built a system in the high intensity area, and also could provide a lead example for the tunnel construction in China and rest of the world, and would have a directive importance to the future construction of tunnels in Qiongzhou Strait, Bohai Strait and Taiwan Strait.