As the development of urban rail transit (URT) picks up speed, more and more attention has been paid to the safety hazards that threaten URT operations. In URT buildings with different fire resistance ratings, the combustion performance and fire resistance limit of their components must meet relevant national standards. It is of certain practical significance to explore the fire propagation law in large modern URT buildings. Considering the peculiarity of URT building fire, this paper carries out numerical simulation and thermophysical feature analysis of fire propagation law. Firstly, the fire propagation features in underground station and section (USS) of URT system were described, and the corresponding control equations were established for mass, momentum, and energy. Then, the factors affecting the attenuation coefficient, including heat exchange coefficient, convection coefficient, and radiation coefficient, were analyzed, and a prediction model was established for temperature attenuation. Experiments were carried out to verify the scientific nature of our numerical simulation of fire propagation law in URT buildings, and obtain the thermophysical properties of fire propagation in URT buildings.

In order to investigate the temperature distribution beneath the subway ceiling, a series of experiments were carried out in a 1:20 small-scale model of a three-level cross-type interchange subway station. The experimental model contains three floors, including two lines of the metro. The experiment results show that the maximum temperature below the ceiling in the cross-type interchange subway station is slightly higher than the maximum temperature below the ceiling under the unconstrained space burning, because the complex structure of the transfer station affects the flow of the fire-induced smoke. The maximum temperature model proposed by Alpert was modified by analysing the experiment results of the highest temperature below the ceiling in the small-scale cross-type interchange subway station, and the new prediction formula for the maximum temperature excess was proposed. When the distance between fire location and side wall is 1.5 times the tunnel height, the modified coefficient of maximum temperature excess is 1.1348 based on the model proposed by Alpert. This study on this issue may benefit the current design of fire protection measures for the platform ceiling.

The fire emergency evacuation in a transfer station, with complicate structure and large number of passengers, is more difficult than that in a single subway station. A three-storey subway transfer station with cross type and island-side transfer form was selected as the research object. Through a field investigation, it was determined that there were 368 occupants should be evacuated in B3 platform and 212 people in B2 platform. And the proportion of adults attached 84%. An agent-based egress simulator was adopted to investigate the effect of different evacuation schemes. Results show that the optimal scheme is to change the arrival field for stair 1 and the stair 4 at the both ends of B3 platform to the concourse in B1 layer directly. In addition, fire curtains on B2 should land to an occupant height in the early stage of evacuation and then fall down to the floor after 240 s. It could improve the evacuation efficiency of the B2 and the B3 train fire, and the evacuation time is decreased by 110 s and 20 s respectively. This study would be helpful for safety evacuation design in a transfer station.