Evacuation of aged persons from inundated underground space

Abstract

Underground is an important space that supports function of cities, such as subways, shopping malls and basement parking. However in consequence a new type of disaster, the "urban flood" menaces these spaces. In the last decade, urban floods struck Tokyo, Nagoya and Fukuoka. When underground inundation occurs, people must evacuate to the ground as soon as possible. But, when such an inundation situation happens, aged persons may not be able to evacuate quickly to ground level. In this paper, the method of safety assessment for aged persons is discussed on the experimental results and flood simulation data in an underground space. As a criterion of the safety evacuation, the specific force per unit width is used in this study. From the result of experiments, it is difficult to implement safety evacuation when the specific force per unit width is over 0.100 m(2) for the aged male.

Measuring Inundation Depth in a Subway Station Using the Laser Image Analysis Method

“…A, and the inundation depth increased simultaneously, as shown in Figure 9a. As aforementioned in Section 2.1, M0 needed to be maintained at less than 0.125 for safe evacuation [1]. However, in Case P1Q1, M0 increased to 0.19 near the center of Sec.…”

“…From the inundation depth measurements, evacuation safety was estimated by using the evacuation time and specific force. To reduce damage to humans from the flooding of underground spaces, it is necessary to calculate the time required for evacuation in case of inundation and prepare evacuation routes [1]. According to the Committee of Countermeasures against Inundation Disasters in Underground Spaces (CCIDUS) [13], the time required for evacuating a person from underground spaces is:…”

“…Furthermore, it is also important to notice which route is safer to evacuate. The aforementioned evacuation safety can be estimated from the specific force (M 0 ), which has been suggested as the criterion to evaluate the safety of a person [1]. The specific force is calculated using the flow velocity and the inundation depth as follows.…”

“…where u is the flow velocity and g is the gravity acceleration. Ishigaki et al [1] reported that normal males can safely escape from an underground space if M 0 < 0.125. To calculate Equation (2), the flow velocity was measured using the large scale particle image velocimetry (LSPIV) method.…”

“…Studies have been conducted to assess the risks to underground spaces in the case of a flood. Ishigaki et al [1] calculated the specific force caused by rainwater when it entered a staircase leading to an underground station. They proposed evacuation routes in case of underground flooding; however, they analyzed the inundation depth calculated by two-dimensional (2D) numerical simulation owing to difficulties in real measurements.…”