Abstract: To ensure the structural safety of operating tunnels, accurately assessing the bearing capacity state of the lining structure is crucial. Due to the concealed nature of tunnel structures, while surface cracks are easy to observe,spatial parameters such as crack depth and propagation patterns are difficult to measure precisely. To address this,full-scale loading failure tests were conducted on plain concrete components, and combined with Digital Image Correlation (DIC) technology, the crack propagation evolution characteristics and bearing capacity evolution of the lining were systematically revealed. The results show that: (1) The crack propagation of plain concrete linings exhibits an evolution pattern of no crack stage, I-type crack stage, and Γ-type crack stage; (2) The initiation of cracks significantly changes the stress state of the structure, leading to stress redistribution and the formation of distinct zoning features; (3) In the region surrounding the cracks, crack propagation has the most significant effect on the stress distribution within a 150 mm range, with less influence on further regions; (4) By comprehensively analyzing the evolution characteristics of bending moment, deflection, load, crack morphology, and bearing capacity, it is proposed to establish the development stage of the Γ-type crack as a control standard for assessing the safety of the lining structure.