Abstract: A case study is conducted on the Pazhou west tunnel project in Guangzhou, China, and the structural type and prefabrication scheme of immersed tunnels in urban core areas are comprehensively compared to select an optimal structural type and prefabrication scheme of immersed tunnels in the urban core area. Then, the advantages and disadvantages of steelshell composite structure (secondary pouring concrete), steelshell composite structure (primary pouring concrete), reinforced concrete structure (new dry dock), and reinforced concrete structure (mobile dry dock) are analyzed and compared. The final scheme is selected as the steelshell composite structure (secondary pouring concrete). The difficulties of dry dock land shortage in the construction project of immersed tunnel in the urban core area can be solved by adopting the structural type of smallsection doublelayer steelshell concrete immersed tunnel and employing advance construction technologies, such as longdistance high freeboard transportation and secondary floating concrete pouring. The method adopted has the advantages of a short construction period, less river dredging, reliable engineering quality, and environmental protection, which will be widely used in the immersed tube tunnel under inland rivers.

Key words: immersed tunnel, structural type selection, element prefabrication, steel shellconcrete composite structure; floating