A Study on Safety at Stairs Flow using the Real-scale Hydraulic Model Experiment

실규모 수리모형실험을 이용한 계단 흐름에서의 안전성에 관한 연구

Abstract

In this study, a real-scale stairway model was constructed to analyze the evacuation safety of human life due to the change of flooded stair flow. In the experiment, the water depth and flow velocity at each stage of the stairs were measured and the specific force per unit width was calculated. Using the calculated the specific force per unit width, the evacuation safety of each steps of stairs according to the change of the flooded stair flow was presented. Finally, the depth of water measured by the experiment and the evacuation safety graph of "Ishigaki" by the specific force per unit width were combined to analyze the evacuation safety by depth. As a result, it has been found that evacuation of adult man is difficult without help at the flow depth of 0.20 m or more. And it has been found that evacuation of adult women and elderly men are difficult without help at the flow depth of 0.15 m or more. Finally, it has been found that evacuation of elderly women is difficult without help at depth of 0.13 m or more.

본 연구에서는 침수된 계단 흐름의 변화에 따른 인명의 대피 안전성을 분석하기 위하여 실규모의 계단 수로 모형을 제작하여 수리 실험을 수행하였다. 실험에서는 계단 각각의 단에서의 수심과 유속을 측정하였으며 이를 이용하여 단위 폭당 비력을 산출하였다. 그리고 산출된 단위 폭당 비력 값을 이용하여 침수된 계단 흐름의 변화에 따른 구간별 대피 안전성을 제시하였다. 실험을 통해 측정된 수심 값과 Ishigaki의 단위 폭당 비력에 따른 대피 안전성 그래프를 결합하여 분석한 결과 계단 흐름 수심 0.20 m 이상에서는 도움 없이 성인 남성의 대피가 어려운 것이 확인되었으며, 수심 0.15 m 이상에서는 성인 여성과 노인 남성이 도움 없이 대피가 어려운 것으로 확인되었다. 노인 여성의 경우 수심 0.13 m 이상에서 도움 없이 대피가 어려운 것으로 나타났다.

Fig. 1. Structure of real-scale experimental stairs model (River Experiment Center in Andong).

Fig. 2. Criteria of safe evacuation described by water depth and velocity. (Ishigaki, 2011)

Fig. 3. Illustration of skimming flow regime and measuring point

Fig. 4. Real-scale experiment and velocity measuring

Fig. 5. Distributions of the specific force per unit width along evacuation route in the normal cases. Double dashed lines are the criterion of u²h/g+h²/=0.125 for safe evacuation and the dashed lines are the limit of 0.250 for evacuation without any help. (Ishigaki, 2008a)

Fig. 6. Comparison of experimental results with previous experiments.

Fig. 7. Distribution of specific force per unit width and the limit of safe evacuation.

Fig. 8. Distribution of specific force per unit width and the difficulties without any help.

Fig. 9. Determination of safe evacuation criteria using depth combined with Ishigaki’s Criteria line of safe evacuation.

Table 1. Specification of experimental stairs model

Table 2. Criteria of safe evacuation presented by the specific force per unit width, M_o (m³/m). (Ishigaki, 2011)

Table 3. Discharge case VS. Average depth & average velocity