Review of Comprehensive Assessment on Mechanical Properties of Water Conveyance Tunnel Linings

To investigate the mechanical behavior of lining structures in water conveyance tunnels under complex working conditions, this study systematically examines the influence of key factors including buffer layer properties, drainage board layout, rheological characteristics of surrounding rock, segment assembly methods, and high internal water pressure on structural performance. Using typical project cases from various regions and combining theoretical analysis, numerical simulations, and field tests, the research demonstrates that under normal load conditions, the outer segments act as the main load-bearing component in double-layer linings, whereas the inner lining's load-bearing proportion increases to 30%-45% under sudden loads. Local installation of drainage boards causes cracks in self-compacting concrete to concentrate within the installation area. Rheological effects in the surrounding rock lead to a gradual increase in axial force in the segments during operation. The longitudinal stiffness of segments with staggered-joint assembly exceeds that of continuous-joint assembly, resulting in reduced stress on circumferential bolts. Under high internal water pressure, the load-sharing ratio of the surrounding rock increases with its elastic modulus. The findings of this review provide theoretical support for the optimized design and long-term safety assessment of lining structures in water conveyance tunnels.