Maximum Smoke Temperature under the Ceiling in Slope Tunnel under Model Test Fires

To research maximum smoke temperature under the ceiling in slope tunnel with longitudinal ventilation and enhance fire protection of the Shiziyang long-sized underwater railway tunnel structure, a series of fire tests were conducted. The tests were conducted in a 1:9 scale model. The model tunnel has a circular cross-section with an inner diameter of 1.1 m and 52.5 m in length. Twenty-one different fire scenarios were simulated. Results indicate the slope of tunnel has an effect on the maximum smoke temperature under the ceiling. Fire test data were compared with the prediction values of the theoretical model. The result shows the deviations in negative gradient tunnel is much bigger than in positive or horizontal, which validates the dependability and limitation of the formulas built by Kurioka. The gradient corrective coefficient was obtained, and the amendment theoretical model with preferable applicability was put forward. The amendment formula can be used for fire protection of tunnel structure.