The construction of the second lining structure of the undersea tunnel between dalian Metro Line 5 and Shuttle has been completed

The tunnel is constructed by the 12.26m diameter "Haihong" air cushion mud balance shield machine. Since the shield was launched on January 18, 2019, the four major problems of "long, large, high and dangerous" have been overcome, and the 1,538 meter karst cave group and 2,882 meter long hard rock excavation have been completed, so that the undersea tunnel will be successfully completed in advance on January 10, 2021.

The internal structure design of the submarine tunnel adopts double lining structure, the outer layer is precast concrete segment structure, the inner layer is cast-in-place concrete structure (including arcs on both sides + air duct plate + middle partition wall and search plate), which is divided into three layers: the upper layer is the exhaust channel, the middle driving layer, and the lower layer is the service layer. The lower opening of the inner track bed is prefabricated and installed synchronously with the shield segment. The remaining lining, middle partition wall and air track plate are constructed in place.

Since the start of construction on March 23, in order to ensure that the construction progress, safety and quality of the second lining structure of the tunnel is fully controlled and the construction is completed on schedule, the project department has taken six measures. The construction of the second lining of the tunnel was completed in advance, which provided conditions for track-laying and decoration engineering construction, and provided guarantee for the trial operation of Dalian metro Line 5 in advance.