Construction of Disaster Damage Index based on Knowledge-based Classification of Landform and Surface Ground

对地面状况的了解是控制自然灾害造成破坏的关键因素。然而，要收集大范围的地面情况信息并不是一件容易的事情。为了解决这个问题，我们考虑了地面条件与地形密切相关的事实。本研究旨在建立一种基于地貌的大面积表层土壤模型的构建方法，以东京以东的千叶县为例，收集整理了大量的土壤调查数据，并将其组织成数据库，建立在地理信息系统上。该数据库还增加了地貌分类。在该数据库的基础上，建立了一些典型的分类地貌标准土壤剖面。然后根据这些土壤剖面计算出动态特性，如放大系数。在此基础上，结合其他已有资料，进行了震害预测。研究发现，地形对预测结果有显著影响，并基于微震和地震动量测，研究了冲积阶地边缘附近地面的动力特性。结果表明，坡顶的谱强度和最大加速度均大于梯田中央和坡脚。研究还发现，主频随距离坡顶边缘的距离而向高频方向变化。由于地形对斜坡附近地面动力特性的强烈影响，在这类地区可能需要进行二维或三维分析。

The knowledge about the condition of the ground is a crucial factor that controls damage due to natural disaster. However, to collect information on the ground condition over a wide area is not an easy task. In order to solve this issue, we have looked at the fact that the condition of the ground is closely related to the landform. This research aims to establish a method of constructing a surface soil model over a wide area based on the landform.By choosing Chiba area, which is located east of Tokyo, a number of soil investigation data have been collected and organized as a database that was constructed on a GIS. Landform classification was also added to this database. Based on this database, a number of standard soil profiles that are typical to classified landform have been constructed. Dynamic characteristics such as amplification factors have then been computed from these soil profiles. Based on this result in conjunction with other existing data, an earthquake damage prediction has been performed. It was found from this study, landform has a significant influence on the prediction.Dynamic properties of the ground near the edge of diluvual terrace were also studied based on microtremor and seismic motion observations. It was found that spectral intensities and maximum accelerations are larger at the top of the slope than in the central part of terrace and at the foot of the slope. It was also found that the predominant frequency changes to higher frequencies in accordance with the distance from the top edge of the slope. Due to this strong influence of landform on the dynamic properties of the ground near the slope, 2-D or 3-D analyses may be necessary in this kind of area.