Recent progress: The construction period of a new excavation tunnel on Metro Line 8 can be advanced by 10 months.

         In order to speed up the construction progress of Line 8, Qingdao Metro has increased the working face in the submarine tunnel of Line 8 and excavated a new tunnel using TBM, which has increased four working faces for the construction of submarine tunnel, greatly improving the construction speed, and can advance the construction period by 10 months.

        The length of the sea section of Line 8 is 7.8 km, and the length of the sea area is 5.4 km. It is a key control project of Line 8. The construction period is tight, the task is heavy and the technical content is high. The submarine tunnel plays an important role in speeding up the subway passage from Qingdao North Station of Line 8 to Jiaodong International Airport of Qingdao. According to the original construction scheme, the submarine tunnels are excavated from East and West ends of Jiaozhou Bay to the middle. The western section is constructed by mining method and the eastern section is constructed by shield method, but the construction period of this scheme is longer. In order to ensure that Line 8 meets the requirements of the overall construction period, Qingdao Metro Group, together with the construction units, has repeatedly studied and organized expert demonstrations to determine the construction scheme of adding a TBM parallel guide hole and opening a new working face.

        The 1 # air shaft on the south side of Landongnan Road in the west of the parallel pilot tunnel is excavated into the Jiaozhou Bay sea area with a total length of 2.1 km. The single shield and double mode TBM construction is adopted, which is the first time that the TBM tunneling machine is used to construct the submarine tunnel in China. TBM started on April 26, 2018 and crossed 970 m long geological fault zone. The fault zone has abundant groundwater, large single point water inflow and mud inclusion. There is no similar construction experience for reference in China. With the joint efforts of Qingdao Metro Group, Line 8 Company, Qingdao Metro Project Headquarters of China Railway and the Second Bureau of China Railway, the excavation was completed 24 days earlier than the construction period of the joint project.

        Up to now, the shield and elevated sections of the airport construction section of Line 8 are connected, and the main structures of Jiaodong Airport Station, Jiaodong Town Station, Citizen Health Center Station and Dayang Station are sealed. The on-site construction is progressing rapidly and orderly.