Abstract: To investigate the corrosion effect of wrapped steel arch frames in the primary support on the mechanical behaviors of the tunnel support system, the bondslip degradation relationship between Ishaped steel and concrete under the corrosion condition is considered, and its constitutive relationship is introduced into ANSYS to simulate the force change law of the tunnel support system under the corrosion condition of steel arch frames. The analytical results show that: (1) When the corrosion rate of steel arch frame is less than 5%, the internal force of steel arch frame, sprayed concrete, secondary lining concrete, and the contact pressure between the primary support and secondary lining change less and are not affected by the corrosion rate. (2) When the corrosion rate of steel arch is 5%~55%, the force behavior and safety of the support system changes greatly. When the corrosion rate reaches 55%, the bond between steel arch frame and sprayed concrete completely fails and the overall forcebearing function between steel arch frame and primary support concrete is completely lost. (3) As the corrosion rate of steel arch frame increases, the surrounding rock load is gradually transferred to the secondary lining, and the secondary lining gradually replaces the primary support and becomes the main bearer of the surrounding rock load.

Key words: subsea tunnel, steel arch frame corrosion, sprayed concrete, bondslip degradation model, support system safety