Study on Cause Analysis and Treatment Measures for Water Leakage Disease in Cold-region Highway Tunnels

To address prevalent issues in highway tunnels in alpine regions, such as water leakage and icing caused by freeze-thaw cycles, and to ensure structural safety and operational efficiency, this study takes the Qiansongba Tunnel on the Chengde-Zhangjiakou High-speed Road as a case study. By integrating field meteorological monitoring, an analytical model of the longitudinal temperature field, and finite element simulations of the temperature field at typical cross-sections, a systematic analysis was conducted on the spatiotemporal distribution pattern of the tunnel temperature field and the characteristics of the freezing depth. The results indicate that the longitudinal temperature inside the tunnel follows a parabolic distribution in winter. Within 1,500 meters from the portal, the freezing depth changes significantly with the longitudinal distance. The primary cause of freeze-blocking in the central drainage ditch, which subsequently leads to water seepage at locations such as sidewalls, the vault, and the arch haunches, as well as icing in the central ditch and on the road surface, is that its designed burial depth is shallower than the local freezing depth. It was verified that a 50-mm-thick thermal insulation layer can reduce the freezing depth in the surrounding rock at the vault by 10-11 cm. Furthermore, the influence of parameters such as the thermal conductivity of the surrounding rock on the temperature field was evaluated. Based on these findings, targeted comprehensive treatment measures combining active and passive methods were proposed, including chemical grouting, groove cutting for drainage, adding thermal insulation layers, and installing electric heating cables. After implementation, the number of leakage points decreased from 40 to 2, representing a treatment effectiveness rate of 95%.