As the cutterhead of the “Conson” shield machine arrived at the boundary mileage at the depth of 105 meters under the sea surface of Qingdao Jiaozhou Bay on October 2, shield excavation for the service tunnel of the second tunnel of Qingdao Jiaozhou Bay was concluded. This marks that shield excavation works for the world’s longest undersea highway tunnel were thoroughly completed.

With a total length of 17.48 kilometers, the second tunnel project of Qingdao Jiaozhou Bay involves a 14.37 kilometers-long tunnel. Given varied geographic conditions of sea areas along Jiaozhou Bay, a combination of “drilling and blasting + shield excavation” was adopted in construction, tunneling was separately carried out from the east and west shores towards Jiaozhou Bay, and the link-up was made under the sea. Two supersized shield machines with a diameter of 15.63 meters worked with another machine whose diameter is 8.18 meters long to advance shield excavation works.

The second tunnel, after completion, will join hands with the existing Jiaozhou Bay tunnel, the Jiaozhou Bay cross-sea bridge and the expressway around the bay to create a comprehensive and multi-layered cross-bay transportation network, thereby ushering Qingdao into “the dual-tunnel era”. (Wang Bingjie)

On October 2, the cutterhead of the “Conson” shield machine arrived at the boundary mileage.