Abstract: To examine the influence of different construction stages of internal lining and shield structure on the distribution of internal force when applying prefabricated, assembled circular open caisson to shield working shaft, an MIDAS-GTS software is employed to establish a load-structure-spring finite element model. Then, the distribution of internal force of the prefabricated, assembled circular open caisson is analyzed in seven working conditions during different construction stages of internal lining and shield structure. Main findings are as follows: (1) The deformation, circumferential internal force, and failures of shear pins of segment can be effectively reduced by increasing the casting height of lining structure and shaft portal leveling area and installing pilasters at shaft portal. (2) The vertical reinforcement of segments with strong boundary constraints or those within the hole-cutting range should be strengthened.

Key words: prefabricated assembly, circular open caisson, construction stages of internal lining, MIDAS-GTS, internal force distribution