Research on tunnel vehicle fire temperature field simulation considering the latent heat of vaporization inside concrete linings

The high temperatures and non-uniform temperature fields caused by fires can lead to the rapid failure of linings, severely affecting tunnel safety. To obtain the temperature distribution of the lining under different fire conditions, simulation research is conducted by CFD technology. First, the fire resistance test of lining is simulated, and a furnace temperature simulation method based on PID control and a lining heat transfer model considering the latent heat of vaporization (LHV) are proposed. Second, the experimentally verified method is applied to a full-scale tunnel model to study the vehicle fire temperature field considering the LHV. The results show that the method based on the PID control can accurately simulate the furnace temperature. By introducing a LHV energy source, the 100 °C temperature plateau within the lining can be effectively simulated to prevent prematurely determining component failure. Compared to traditional methods, the lining-gas heat exchange boundary considering the LHV is more accurate. The temperature rise at the lining surface and rebar is slower, with maximum temperature differences of 80 K and 125 K, respectively. The aim of this research is to provide a complete temperature rise and fall process for the fire protection analysis and design of tunnel linings.