Experimental study on the maximum temperature under the ceiling in a metro depot with one end closed

Abstract

Metro systems have been widely developed in many countries all over the world, and its operation safety and environmental control are the key issues need to be investigated, especially for the cases of a fire scenario. In this work, a 1/10th scaled subway tunnel with one end closed was constructed to study the ceiling temperature profiles in the metro tunnel when a fire occurs, and the temperature prediction model was proposed. The heat release rates (13 kW-19 kW) and tunnel slopes (0 %-3 %) were changed, and the horizontal temperature in both the longitudinal and transverse direction under the metro tunnel ceiling were measured. The results showed that the temperature distribution in the longitudinal direction were divided into three stages. The dimensionless temperature rise decreases exponentially with the distance from the plume impingement point, and the attenuation rate increases with the tunnel slope. The maximum temperature of the lateral corresponds to the location at the longitudinal centerline of the tunnel, and the temperature decreases from the highest value and presents a symmetrical distribution. Through dimensional analysis, three prediction models were constructed to forecast the temperature under the ceiling at each stage for different HRRs (heat release rates) and tunnel slopes, and the predicted models were verified by the experimental data, and showed good agreements.