HAZARAD ANALYSIS OF SMALL UNDERGROUND SPACE IN URBAN FLOOD AND STUDY OF COUNTERMEASURES

本文的主要研究成果如下：建立了小型地下空间淹没分析的三维数值模拟模型。模型采用VOF方法。模型进行了验证，比较几个计算结果与实验数据的足尺楼梯模型和1/15板条箱地下室模型，包括两个楼梯，走廊和五个房间。结果表明，该模型能较好地模拟地下室的淹没流动行为。利用楼梯和门两个真实的尺寸模型对地下空间人员疏散进行了研究。通过楼梯间的实验发现，地面0.3m的水深是安全疏散的极限，服装也与人员疏散有关。此外，还引入单位宽度轮胎比数作为走廊和楼梯间安全疏散的新评价标准。当单位宽度的比尺大于0.125m^2时，安全疏散难以实施。通过对闸门的试验发现，闸门前0.3 ~ 0.4m的水深是闸门顺利开启的极限。通过城市洪水模型与二维地下水淹没模型的模拟结果，我们发现在每个入口处设置台阶是降低地下水淹没风险的有效措施之一，特别是对于短时强降雨。

The main results obtained through this research are as follows.A three dimensional numerical simulation model is developed for inundation analysis in a small underground space. VOF method is used in the model. The model is verified, comparing several computation results with the experimental data of a full-scale stairs model and of a 1/15-crate basement model comprising two stairs, corridor and five rooms. It is found that the model can well simulate the inundation flow behavior in the basement. We conclude that the model can be applicable to evacuation analysis in a small underground space.Evacuation from underground space has been investigated by using two real size models of staircase and door. From the experiment of staircase, we find that the water depth of 0.3m on the ground level is the limit of safe and easy evacuation and that clothes are also related with evacuation. In addition, specific tire per unit width is introduced as a new criterion to evaluate safety evacuation in both corridor and staircase. It is difficult to implement safety evacuation when the specific faro per unit width is over 0.125m^2. From the experiment of door we find that the water depth in between 0.3m and 0.4m in front of the door is the limit to open it without difficulties. Also, we have to keep in mind that evacuation by children or elderly people is more difficult than that by adults.Through the simulation results by the integrated urban flood model with 2-D underground inundation model, we find that setting of step at each entrance is one of the effective measures to reduce the risk at underground inundation, especially for heavy rainfall for a short time.