Many floods caused by heavy rainfalls and typhoons hit Japan in recent years, and some floods attacked fully urbanized areas. Tokyo, Nagoya and Fukuoka were inundated by urban floods, and some parts of flood water intruded into underground spaces. During the floods, underground shopping arcades and subway stations were inundated. The inundation in underground space is one of the problems to resolve urgently. One of effective measures to reduce the damage of flood disaster is quick evacuation from the underground spaces. In this paper, evacuation from underground spaces has been tested by using real scale models of staircases and doors. From the results, it is found that water depth of 0.3m on the ground is a critical depth for evacuation from underground space through staircases and 0.4m deep in front of the door is the limit to open the door.
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.
The effectiveness of bandal-like structures (BLS) for the formation or restoration of navigational channel is tested. The basic feature of BLS in terms of flow and sediment control are clarified using simplified mobile bed experiments where a series of such structures are installed on both side banks . Based on the experimental results and flow visualization, simplified analytical model for the prediction of main channel degradation (as a measure of navigational channel formation or restoration) is developed and verified using experimental data. The model predicts the experimental results reasonably well .
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