Abstract: In order to study the smoke spread characteristics and smoke temperature distribution in construction tunnel fire under different longitudinal fire source locations and heat release rates, a reduced-scale construction tunnel model was established by using the model⁃scale experiment method. The longitudinal and vertical smoke temperature distribution under the tunnel ceiling was measured. The results show that under the condition of natural smoke exhaust, the smoke can not be discharged in time inside the construction tunnel, and then hit the wall to form a rebound smoke flow, which continuously settled to about 0.1 m above the tunnel floor. The longitudinal fire source location has great influence on the smoke spread speed and the longitudinal temperature attenuation rate. As the fire source moves to the left closed end, on the right side of the fire source, the smoke spread speed increases and the longitudinal temperature attenuation rate decreases. For the left side of the fire source, the smoke spread speed decreases and the longitudinal temperature attenuation rate increases. The dimensionless vertical smoke temperature rise accords with the self-similarity law, showing a composite function distribution. Considering the influence of longitudinal fire source location and heat release rate, the variation of the smoke spread velocity is summarized, and the experimental correlations are established to predict the vertical smoke temperature distributions under the tunnel ceiling.

Key words: construction tunnel, fire, smoke spread, temperature distribution, natural smoke exhaust, experimental study