Study on fire smoke flow law on platform layer of deeply buried subway stations with escalators arranged in the same direction

Taking a deeply buried subway station with the escalators arranged in the same direction as the research object, a three-dimensional numerical model is established using FDS, and the accuracy of the numerical model is verified with measured data. The variation laws of smoke height, smoke temperature distribution and smoke front velocity on the platform layer under different fire source locations and different smoke exhaust air volumes are discussed. The research results show that mechanical smoke exhaust can inhibit the longitudinal spread of smoke, while the entrainment effect caused by the downward slanting airflow along the escalator, which is opposite to the direction of smoke flow, will cause the smoke to sink in the area near the escalator opening. The smoke temperature distribution under the platform roof along the length of the platform conforms to the decay law of exponential function. Due to the destructive effect of the horizontal partial velocity of the downward slanting airflow along the escalator on the smoke layer, when the smoke exhaust air volume is greater than 80 m3/s, the temperature attenuation rate of the smoke flowing towards the left end of the platform is faster than that flowing towards the right end of the platform. The smoke front velocity decreases exponentially with the increase of the smoke exhaust air volume. When the smoke exhaust air volume increases from 0 m3/s to 120 m3/s, the smoke front velocity of the smoke flowing towards the left end of the platform decreases more than that flowing towards the right end of the platform.