Experiment Research on Smoke Temperature Properties Lower Ceiling along Tunnel at Different Longitudinal Ventilation Velocities and Tunnel Slopes

摘要

To investigate smoke temperature properties lower tunnel ceiling by longitudinal ventilation velocities and different tunnel slopes when fire occurred in a tunnel, a series of fire tests were conducted in a reduced scaled model tunnel. The model tunnel was 52.5m length, and it had a circular cross-section with an inner diameter of 1. 1m. A methanol pool was employed as a fire source. Seven tunnel slopes and four longitudinal ventilation velocities were used to simulate different fire scenarios. The smoke temperatures lower the tunnel ceiling were measured and analyzed. The variation laws of smoke temperature lower the tunnel ceiling were gained, such as the temperature at different distance from the fire source varying with time and with longitudinal distance, the maximum smoke temperature above the fire source. The results show that negative slope has bigger effect on smoke temperature under the same ventilation velocity, and the effect is more as the negative gradient increases. In the same slope tunnel, smoke temperature gradually diminishes as ventilation velocity increases. When the longitudinal ventilation velocity is 1.34 m/s, the smoke temperature of the upstream section of fire source is tendency to normal temperature.