Abstract: In order to explore the bearing characteristics of the double-layer lining structure of subsea shield tun? nels, taking the Jintang Subsea Tunnel on Ningbo-Zhoushan Expressway 2nd as an engineering background, this study considers the bond damage mechanics effect at the interface of the double-layer lining. A three-dimensional elastoplastic damage model for the double-layer lining structure of shield tunnels is established to study the com? bined bearing mechanical characteristics of the tunnel segment structure and secondary lining under high water pressure conditions, and to clarify the safe bearing state of the double-layer lining structure. The research results show that: (1) Compared with the single-layer segment scheme, the ultimate bearing capacity and structural stiffness of the overlapped double-layer lining structure increase by 66.3% and 200.8%, respectively, while the composite lining has little impact on its structural bearing capacity and lateral stiffness, with increases of only 7.1% and 16.9%, respectively. The greater the loss of interface bond strength, the lower the ultimate bearing capacity of the tunnel structure and the worse its deformation adaptability; (2) During the bearing process of the overlapping struc? ture, both the tunnel segment and the secondary lining structure are at risk of exceeding their ultimate bearing ca? pacity. The arch bottom of secondary lining presents a small eccentric tensile state, where through cracks are likely to occur; the arch waist of secondary lining presents a small eccentric compressive state, where crush failure is like? ly; the segment and secondary lining of the composite structure both show a large eccentric compressive state, and no through cracks are generated, but there is a risk that the width of structural cracks may exceed the code limits; (3) Based on the deformation failure characteristics of the secondary lining of the overlapping structure and the residual bearing capacity index of the composite structure, safety control indicators for the double-layer lining structure of shield tunnels are proposed.