Abstract: To explore the applicability of circular support and side truss support for specialshaped foundation pit in soft soil area and the safety control method for the large deformation, a study is conducted on the support scheme for a deep foundation pit of a metro station with connection gallery under complex environmental conditions. First, the support system for the foundation pit is studied. Second, the disadvantages of circular support for specialshaped foundation pit are compared. Finally, the numerical simulation and field monitoring results are analyzed. Conclusions are drawn as follows: (1) Due to the uneven stress of circular support, the circular support system should be avoided when the shape of foundation pit is irregular under complex environmental conditions in soft soil. (2) The project should be well planned and prepared in advance to reduce large deformation of foundation pit. (3) The internal support should be added in design phase of foundation pit when the excavation condition is limited, so as to improve the antideformation capacity of foundation pit. The basin excavation mode can be adopted to reduce the large deformation of foundation pit.

Key words: soft soil area, metro station with connection gallery, side truss + internal support, circular support, numerical analysis, deep foundation pit, field monitoring