Experimental study of smoke character in long-sized railway tunnel

To investigate fire behavior in tunnel and improve fire protection in the ShiZiYang long-sized underwater railway tunnel, a series of fire testing were conducted. The scopes of the testing include temperature distribution and influential length of back-layering smoke flow in the tunnel under fire circumstance. The testing was conducted in a 1∶9 scale model. The model tunnel had a circular cross-section with an inner diameter of 1.1 m and 52.5 m in length. Thirteen different fire scenarios were simulated. Results indicate, as for longitudinal temperature distribution, the maximum temperature lies in fire source and the temperature of hot smoke decreases with the distance from fire source. Furthermore, the maximum temperature in fire source decreases and influential length of back-layering smoke flow decrease creases when air velocity applied in tunnel or tunnel slope increases. Based on the experimental results, suggestions on structure protection, critical ventilation velocity under fire scene are proposed.