Influences of staircase pattern and flood blocking board setting on pedestrian vulnerability in urban underground staircase floodwaters

In order to study the hydrodynamic process of surface floodwater intrusion into different types of staircases and pedestrian safety evacuation situations (also known as pedestrian vulnerability), four different types of staircases, namely L-shaped, U-shaped, double split shaped and double combined shaped, are designed, and F which is equal to the square of v multiplied by h (v and h are the floodwater velocity and water depth on the staircase respectively), is used as the danger index to measure the pedestrian vulnerability characteristics in staircase flooding. It is found that the double split type of the staircase has the largest safety area range, followed by U-shaped and L-shaped stairs, and the double combined type of the staircase. Furthermore, the impact of adding a flood blocking board at the entrance of the staircase on pedestrian vulnerability is discussed, and it shows that a high flood blocking board leads to a large reduced rate in pedestrian vulnerability. The obtained results might provide a reference for the design and planning of underground space staircases, as well as flood control and evacuation in underground spaces.