Abstract: To investigate the effect of effective lining bearing thickness loss induced by severe corrosive environment and construction defects on the tunnel structural safety, a twodimensional lining force analytical solution model is established based on elastic foundation curved beam theory and spatial state method. The Laplace numerical transformation is used to solve the internal force and displacement at each position of the lining, and the results are compared with that of the numerical model under the same working conditions. The effective secondary lining thickness loss is simulated by discounting the local secondary lining thickness and adjusting the discount range. The results reveal the following: (1) Increasing the range and degree of secondary lining thickness loss leads to a significant reduction in the crosssectional bending moment at the thickness loss. However, the change in axial force is small. (2) The influence of secondary lining thickness loss on the safety coefficient is mainly concentrated in the area near the thickness loss. As the loss range increases, the bending moment in the thickness loss area shows a concave parabolic decrease, and the safety coefficient experiences sudden drop, rebound, and stability. (3) When the loss thickness is small, the safety coefficient is less affected by the change in axial eccentricity, and the effective bearing thickness is approximately linear. After the deterioration thickness continues to increase, the gain in safety coefficient by reducing axial eccentricity increases rapidly, and when it is greater than the deterioration benefit of the bearing crosssectional area, the calculated safety coefficient increases. However, there is a risk of local structural deformation damage.

Key words: operational tunnel, secondary lining, loss of lining thickness, effective bearing thickness, elastic foundation curved beam, Laplace transform, safety factor