Abstract: With the development of economy and the increasing number of highrise buildings, the dimensions of deep excavation projects become larger and larger, and the foundation construction duration becomes longer and longer. Especially, excavated areas in the deep excavation in seasonal frozen soil areas will inevitably encounter the geohazards induced by the cold weather. In order to study the deformation characteristics of supporting structures in the deep excavation in seasonal freezing areas under the effect of freezing and thawing cycles, numerical analyses are performed for the support system of a deep excavation project in Changchun. It is found that the freezing effect will reduce the ground subsident at the top of the excavation; increase the bottom heave at the excavated area and increase the horizontal displacement of the supporting structure and the axial force of the reinforced concrete internal support. After the thawing effect, the ground subsidence, the bottom heave at the excavated area, the horizontal displacement of the supporting structure and the axial force of the reinforced concrete internal support are all greater than those before the freezing. By comparing with the construction monitored data, it is found that the general trend of simulated values and monitored values are consistent, and the effect of freezethaw cycle has produced unrecoverable deformation in the deep excavation supporting structures.

Key words: deep excavations, deformation, numerical analysis