Abstract
Unlike shallow-buried tunnel projects such as subway tunnels, deep-buried water diversion tunnels are characterized by complex stress conditions, significant disturbances during construction, complex mechanisms of action of various components, and severe consequences of failure. Therefore, studying the seismic response and damage characteristics of hydraulic tunnels under complex conditions is of significant practical importance in ensuring their long-term safe and stable operation. This paper takes a deeply buried water diversion tunnel section of a water system interconnection project as the research object. Based on the series characteristics of important tunnel components, a seismic vulnerability model of the tunnel is constructed. By establishing a three-dimensional numerical model, the seismic vulnerability of the deeply buried water diversion tunnel is analyzed, taking into account external complex structural stress, construction disturbance, internal and external water pressure, material parameters, and uncertainties in seismic input. The following conclusions are drawn: Under the same earthquake magnitude, the anchor structure is more prone to damage than the segment structure; when the earthquake PGA does not exceed 0.4 g, the impact of the earthquake on the tunnel safety is extremely limited; when the PGA is greater than 1.2 g, the probability of the water diversion tunnel being in a moderate or severe damage state exceeds 44%, at this time, necessary engineering measures should be taken to focus on reinforcing the weak parts of the tunnel; reducing the burial depth is more effective in improving the structural stability of the water diversion tunnel under seismic loads than increasing the tunnel support strength. On average, for every 10 m reduction in tunnel burial depth, the probability of the tunnel being moderate or severe damage decreases by 7%, and for every 15% increase in tunnel support strength, the probability of tunnel damage decreases by 3%.