Abstract: The evolution mechanism of load-sharing ratio of secondary lining under  steel arch frame corrosion of subsea tunnels is crucial for long-term safety of the tunnels. Herein, a three-dimensional solid load-structure model of the primary support-secondary lining under corrosion effect of the steel arch frame is established based on a subsea tunnel. The variation patters of the contact stress between the primary support and secondary lining, the safety of the secondary lining, and the load-sharing ratio under different corrosion degrees of steel arch frame are examined. The results indicate the following: (1) The contact stress between the primary support and secondary lining sharply increases as the corrosion rate of steel arch frame increases from 0% to 60%; the contact stress at the crown, arch shoulder, sidewall, arch foot, and invert increases by 46%, 45.11%, 49%, 47.42%, and 44%, respectively. The corresponding safety factor of the secondary lining shows a downward trend. (2) The load-sharing ratio of the secondary lining increases from 0.54 to 0.63, with an increase of 16.67%, as the corrosion rate of the steel arch frame increases from 0% to 60%. (3) A prediction formula for the load-sharing ratio of the secondary lining is established by comprehensively considering the corrosion rate of the steel arch frame, the thickness of the secondary lining, and the elastic modulus of the secondary lining.

Key words: subsea tunnel, steel arch corrosion, secondary lining, mechanical evolution, safety factor, load-sharing ratio