Experimental and numerical study on fire-induced smoke temperature in connected area of metro tunnel under natural ventilation

Abstract

Previous studies have usually focused on an ordinary single tunnel fire. However, the structural effect of metro connected tunnel area on the smoke temperature still needs to be clarified. Therefore, this paper aims to modify the current model for predicting the fire-induced smoke temperature considering different sloped conditions in main and connected tunnels. Small-scale and full-scale experiments were conducted with the main tunnel and connected tunnel being horizontal, then extended numerical simulations were performed to clarify the common inclined effect of both the main and connected tunnel on the smoke temperature under natural ventilation. The results show that, maximum smoke temperature varies with a reduction or enhancement of the heat accumulation caused by slope conditions in both the main and connected tunnels. The dimensionless temperature profiles along the smoke spread depends on the slopes of current tunnel itself and are affected little by slopes of another connected one. Prediction models for the maximum smoke temperature and longitudinal temperature profiles were further developed by taking the main and connected tunnel slopes into account. Moreover, it performs good fitting degree for the correlated temperature profile and the predicted maximum smoke temperature agree well with experimental and simulated results, which provides an easy-to-use method for estimating smoke temperature in a fire prevention design or emergency rescue in such metro system.