<p>The presence of voids behind tunnel linings creates local discontinuities in the interaction between the surrounding rock and the lining, thus compromising operational safety and structural reliability. This study investigates void-induced damage and crack propagation behaviour in the composite lining of the Feilingshan Tunnel, and develops a three-dimensional ground-structure interaction numerical model based on the extended finite element method (XFEM). The study systematically analyzes the effects of void length, circumferential extent, and spatial position, as well as the coupled influence of bilateral voids on the stress characteristics and crack development. The results indicate that increases in void size significantly intensify the tensile stress concentration below the void and substantially disturb the contact stresses between the primary support and secondary lining. The tensile stress concentration and bending moment variation induced by voids at the arch waist are most significant, and the tensile stress concentration at the inner edge of the secondary lining near the vault exceeds that of the primary support. When voids are symmetrically distributed in both tunnels, the lining structure response exhibits a mirrored distribution, leading to a higher risk of cracking compared to a single void; conversely, when voids are asymmetrically distributed, changes in the void position on one side have only a marginal influence on the stress and failure modes of the other side. Voids behind the lining significantly decrease the initial cracking load and modify crack orientation and propagation patterns. The findings provide a theoretical reference for preventing and controlling void-induced damage in the composite lining structures of large section small clearance tunnels.</p>