Abstract: The common structure section between high-speed railway tunnel and airport poses great challenge to design work. The Airport No. 2 tunnel on the Jinan-Binzhou high-speed railway crosses underneath the ground traffic center (GTC) and Terminal 2 of Yaoqiang airport in Jinan, China, and faces various challenges, such as close to the airport, excessive upper loads, varying tunnel structures, high underground water level, and low foundation bearing capacity. Through data investigation, comparative analysis, numerical simulation, and on-site measurement, the design scheme of the co-constructed section of Airport No. 2 tunnel, GTC, and Terminal 2 is studied. The findings include: (1) The combined support method of using concrete trusses, diagonal bracing, steel supports, and steel support servo systems in a zoned and segmented approach effectively controls the deformation of the "horn-shaped" deep foundation pit and enhance the efficiency of pit excavation. (2) The scheme of using transfer beams in the upper structure facilitates the stress distribution of the tunnel structure and load transmission, thus reducing the size of the tunnel structure and save engineering investment. (3) The circular arch structure with multiple boxes straight wall flat top bears super large loads. (4) The scheme of uniformly arranging long and short piles at the bottom of the tunnel effectively controls the settlement and deformation of the tunnel structure.

Key words: high-speed railway tunnel airport, common structure system, structural design, foundation pit support, settlement control