The effect of the wall lining on road tunnel fire

As in the world, there are many tunnels on the highway in Turkey, and their number is gradually increasing. Although the road tunnel is convenient in terms of transportation, it is a very difficult structure to operate and ensure its safety. It is necessary to determine what will happen in the tunnel in a negative situation such as a fire in tunnels that are considered as a volumetrically closed box, and the necessary safety measures should be taken by considering possible scenarios. Along with life safety, knowing the extent to which the systems inside will be affected is also of great importance in terms of determining the measures to be taken and the systems to be installed. The basis of this study is the study of the possible effects of the distribution of high temperature in a fire in a tunnel. In addition, it has also been investigated how any layer to be added on concrete walls will change the temperature distribution. The transfer of heat from the wall surface due to fire and its effects on layers with different properties have been studied. The model used in the study is designed as two layers, since normally the tunnel structure has concrete surfaces embedded in a mountain of soil density. As the third layer, three separate layers were added, namely Calcium-silicate, Aluminum and Nickel, and the heat transfer characteristics were studied. Numerical analyses were performed using the ANSYS/FLUENT program and the standard k-ɛ model. Modeling was performed on a hot gas with mass flow based on tunnels that do not have any fan, that is, forced ventilation, and solutions were carried out depending on time. In the study with the third layer, it was shown that the greatest heat transfer was achieved in Aluminum and Nickel layers, and the results were very close. It has been observed that thermal inertia, density and specific heat are also factors along with the heat conduction coefficient on the results. In addition, similar results were obtained with a three-layer Calcium-Silicate layer and a two-layer layer.