Research on Cracking Mechanism and Crack Extension of Diversion Tunnel Lining Structure

Tunnel systems are often confronted with issues such as cracks, water seepage, and exposed tendons, all of which compromise their structural integrity. This study utilizes an advanced robotic system equipped with a 3D laser scanner to capture data on visible lining defects. By analyzing the distribution of defects across various tunnel segments, we explore the mechanisms underlying structural cracks. Finite element software is employed to assess stress, deformation, and crack progression within the tunnel linings. The result found that the diversion tunnel’s segments exhibit notable variations: 66.0% of the defects are concentrated in the upper flat section, while 34.0% are found in the inclined shaft segment. Cracks, primarily located in the vault area, characterize these defects. Under water pressure, stress deformation in the intact lining follows a linear escalation pattern. Specifically, after the formation of cracks measuring 0.1 m, 0.2 m, and 0.3 m, circumferential stresses increase by approximately 4.50%, 9.10%, and 15.10%, respectively. Numerical simulations reveal significant stress concentration near the cave entrance at the upper flat break. Crack propagation at the arch crown is found to pose a greater risk than at the sides of the arch waist. These findings offer valuable scientific insights and practical implications for improving safety and enabling intelligent monitoring of power station tunnels.