Development of Earthquake Resistant Evaluation Method for Decrepit Small Earth Dam using Non-Destructive Exploration

日本政府预计，在不久的将来，四国岛将发生南开地震。香川县首府高松市在90至150年间的南开地震中遭到严重破坏。最近的地震表明，如果发生地震，许多灌溉池塘堤坝可能会遭到严重破坏。震害与路基条件密切相关。因此，在考虑结构的抗震设计时，明确堤防条件是非常重要的。本研究的目的是通过面波勘探和地震动测量来估计灌溉池塘堤岸的运动放大。本研究对四种类型的灌溉池塘进行了分类。平原池塘的S波波速小，山脚下的池塘S波波速大。而对于冲积层的S波速，不同类型的池塘差别不大。护岸S波速与护岸高度呈正相关关系。同样，优势周期与岸高呈正相关关系。但是，放大与银行优势周期之间存在负相关关系。基础和岸坡的振动特性对岸坡的运动放大有很大影响。

The Japanese Government anticipates an occurrence of a Nankai earthquake in Shikoku Island in the near future. Takamatsu, the capital city of Kagawa Prefecture, has been serious damaged by Nankai Earthquakes at intervals from 90 to 150 years. Recent earthquakes have suggested that many irrigation pond embankments could be seriously damaged in the event of an earthquake. The seismic damage is closely related to the embankment condition. It is therefore very important to clarify the embankment conditions when an earthquake-resist design of a structure is considered.The objective of this study is to estimate the motion amplification of bank of irrigation ponds by surface wave exploration and microtremor measurement. In this study, four types of the irrigation ponds were classified. S-wave velocity of bank is small in the ponds situated in plain and large in the ponds situated in the foot of the mountain or mountain. However, with regard to S-wave velocity of alluvium, the difference in types of the ponds is small. The relation between S-wave velocity of bank and height of bank has positive correlation. Similarly, the relation between predominant period and height of bank has positive correlation. But, the relation between amplification and predominant period of bank has negative correlation. Motion amplification of bank is strongly affected by the vibration characteristics of the foundation and the bank.