Vulnerability to Underground Inundation and Evacuation in Densely Urbanized Area

Ishigaki, Taisuke; Kawanaka, Ryuji; Ozaki, Taira; Toda, Keiichi

doi:10.20965/jdr.2016.p0298

Cited by 11 publications

(4 citation statements)

References 7 publications

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“…When the ground material is consistent, the height and velocity of the flood water is the most important influence on the stability of people walking in the flood [57]. Ishigaki, Ozaki [58] set up escape tests for a variety of people in floods based on these two indicators and derived the escape judgment function (see Equation (2), given again below) and the critical escape conditions for each type of person, which are summarized, in this paper, for each type of person alone (Table 2). Since it is more difficult for people to escape up the steps during a flood than to the rest platform, and the flood flow velocity on the rest platform is lower, this paper calculated and plotted the change in escape function F(v, h) on the edge surface of each step of a staircase with four rest platforms during 0.3, 0.25, 0.2, and 0.15 m high floods (Figure 12), and the curve between the two break points in the figure represents a flight.…”

Section: Hazards Of Escaping For People In Flood Intrusion Staircase ...mentioning

confidence: 99%

Flow Pattern and Escape Hazards of People from Flood Intrusion into the Staircase of Underground Spaces with Multiple Rest Platforms

Lin,

Hu,

Lin

2024

Buildings

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While urban underground space is being built and developed at a high speed, urban flooding is also occurring gradually and frequently. Urban water, in many disasters, has intruded into underground spaces, such as subway stations, often leading to serious casualties, in which it is crucial for people to be able to escape from the staircases. In order to enable and guide the escape of people in underground floods, a staircase model with multiple rest platforms, applicable to common entrance and exit staircase forms, was constructed. The realizable k-ε turbulence model, coupled with a volume of fluid (VOF) method, was used to simulate and analyze the flow patterns when floods of various heights intrude into the structure. The effects of rest platform settings on the ejection phenomena and flow velocity changes in flood flows were summarized. The change rule of flood flow velocity on the stairs under different flood heights and stair heights was summarized, and a linear relationship between the peak flood flow velocity and the location of the peak flow velocity point on each flight of stairs was derived. Combined with the formula of the critical conditions for people to escape upwards in the flood, the proposed escape conditions for staircases with multiple rest platforms were proposed, which provide a basis for guiding the evacuation of people in times of disaster.

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Section: Hazards Of Escaping For People In Flood Intrusion Staircase ...mentioning

confidence: 99%

Flow Pattern and Escape Hazards of People from Flood Intrusion into the Staircase of Underground Spaces with Multiple Rest Platforms

Lin,

Hu,

Lin

2024

Buildings

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“…Recently, various models and techniques were applied to predict flooding, inundation, and its vulnerability in advanced approaches [6][7][8][9]. However, there is a lack of hydrodynamic-based modeling that analyzes, in detail, the flow through underground access stairways or the flow characteristics through underground structures that link upper and lower layers in complex underground areas.…”

Section: Previous Studies and Selection Of Model Dimensionmentioning

confidence: 99%

Numerical Computation of Underground Inundation in Multiple Layers Using the Adaptive Transfer Method

Rhee

Song

2018

Water

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Extreme rainfall causes surface runoff to flow towards lowlands and subterranean facilities, such as subway stations and buildings with underground spaces in densely packed urban areas. These facilities and areas are therefore vulnerable to catastrophic submergence. However, flood modeling of underground space has not yet been adequately studied because there are difficulties in reproducing the associated multiple horizontal layers connected with staircases or elevators. This study proposes a convenient approach to simulate underground inundation when two layers are connected. The main facet of this approach is to compute the flow flux passing through staircases in an upper layer and to transfer the equivalent quantity to a lower layer. This is defined as the 'adaptive transfer method'. This method overcomes the limitations of 2D modeling by introducing layers connecting concepts to prevent large variations in mesh sizes caused by complicated underlying obstacles or local details. Consequently, this study aims to contribute to the numerical analysis of flow in inundated underground spaces with multiple floors.

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“…Nowadays, a variety of models and approaches are used to determine inundation and flood damage [6][7][8][9]. However, there is a lack of hydrodynamic-based modeling that analyzes, in detail, the flow through underground access stairways.…”

Section: Introductionmentioning

confidence: 99%

Inundation Risk Assessment of Underground Space Using Consequence-Probability Matrix

et al. 2019

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Increases in the frequency and severity of extreme rainfall might cause catastrophic submergence of underground spaces. Therefore, it is essential to predict the flood risk for proactive design. This study presents the methodology of acquiring risk level considering both flood intensity and evacuation difficulty. The flood momentum was computed by a 2D hydraulic flow model, and the flood intensity (FI) was employed to evaluate the consequence of flooding. To investigate the level of evacuation difficulty, the spatial layout of rooms, together with walking speed, were considered in the risk analysis process. If stormwater runoff enters an underground space, zones far away from the inlet usually have low risk levels. However, when the level of evacuation difficulty was considered, the risk level was dependent on the evacuation distance and location of the inlet and exit. If people are in zones with a risk level of 4 or 5, a rapid evacuation is necessary for preventing human casualties. The proposed methodology incorporated with the inundation model can be applied to any underground space regardless of the location of stairs, the number of exits, shape of rooms, or layout of the floor. Consequently, it will contribute to mitigating flood damage in an underground space.

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Vulnerability to Underground Inundation and Evacuation in Densely Urbanized Area

Cited by 11 publications

References 7 publications

Flow Pattern and Escape Hazards of People from Flood Intrusion into the Staircase of Underground Spaces with Multiple Rest Platforms

Flow Pattern and Escape Hazards of People from Flood Intrusion into the Staircase of Underground Spaces with Multiple Rest Platforms

Numerical Computation of Underground Inundation in Multiple Layers Using the Adaptive Transfer Method

Inundation Risk Assessment of Underground Space Using Consequence-Probability Matrix

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