High-Temperature Resistance of Galvanized Steel Corrugated Panel Partitions in Inclined Shafts of Extra-Long Road Tunnels

This study investigates high-temperature resistance of galvanized steel corrugated panel partitions in the inclined shafts of extra-long road tunnels under tunnel fire conditions. Numerical simulations and laboratory experiments were conducted to evaluate the thermal behavior of galvanized steel and to analyze the influence of fire scenarios on the temperature distribution within tunnel ventilation shafts. The experimental results show that at 400 °C, the galvanized coating deteriorates and loses its protective function. Below this temperature, the coating largely remains intact and continues to protect the base material. However, mass loss increases significantly once the temperature exceeds 250 °C, indicating potential concerns for long-term durability. The simulation results show that temperatures near the shaft partition increase with higher heat release rates (HRR), lower exhaust velocity, and shorter connecting duct lengths, but the maximum temperature does not exceed 250 °C. Temperatures along the shaft height remain nearly uniform, while near the shaft entrance they decrease rapidly with distance from the fire source. Compared with reinforced concrete partitions, galvanized steel corrugated panels are lighter, easier to install, and require less material. This study provides a systematic assessment of their high-temperature performance in inclined shafts, supplying evidence for their application in tunnel fire protection design.