Xu Zhang, Yewei Dong, Youjun Xu, Hong‐Gang Wang
The permeable ribbed double-arch tunnel is an innovative multi-arch environmentally friendly tunnel designed for mountainous areas. However, inevitable lining voids caused by structural complexity and construction variability critically compromise their structural integrity, while research gaps persist regarding failure mechanisms and risk assessment. This study used scaled failure model tests to compare void-affected and intact specimens and quantify the impact of voids. The results show that, compared to the concealed inner tunnel structures, the cut-and-cover chambers exhibit significantly higher vulnerability. Due to lack of surrounding rock confinement and longitudinal constraints, the rib arch structures show severe cracking phenomena at both ends and central sections, with the central zone preferentially developing through-thickness cracks—confirmed as the structurally most critical weak area. Local voids induce location-dependent asymmetric soil pressure distribution, causing earlier initiation and intensified propagation depth of edge cracks. Crucially, the reduction in lining's load-bearing capacity near void regions significantly amplifies rib-arch bending moments. When voids approach ribs, structural failure acceleration occurs. This achievement provides a theoretical basis for precise void detection in vulnerable zones and offers scientific guidance for reinforcement design of such tunnels.