Abstract: The special jacking structure is constructed based on the field boundary conditions, construction scheme, and optimization design concept to achieve the installation requirements of precast segments in the arch of tunnel secondary lining and the transfer of precast segments to segment assembly trolley safely and conveniently. Furthermore, the structural scheme of the jacking structure and the lifting cylinders′ selection are discussed in detail, and the stability of the jacking structures′ lifting cylinder is examined and verified. Finally, using mechanical analysis, the suitable installation position of the jacking structure is identified, and the strength of the sidewall lining gantry system is verified utilizing the finite element method. The jacking structure is currently used on the construction site of the Hujiagou tunnel project of the Chongqing railway hubs′ eastern loop line, where it is assisting in the assembly construction of 11 groups of precast segments. The following points show the theoretical analysis and field application: (1) The jacking structure is welldesigned, and the strength and stability can achieve the requirements of onsite construction. (2) There is no malfunction of the jacking structure during the appropriate period, ensuring that the precast segments of the arch are assembled smoothly.

Key words: railway tunnel, secondary lining, arch prefabricated segment, jacking structure