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近年のため池改修では，ベントナイト系遮水シート（GCL）を用いて改修する事例が増えている．既 往の研究で GCL および従来の前刃金工法を用いた堤体を対象とした実大規模震動実験で，両者の耐震 性が検証された．実際の施工では，GCL を継ぎ足す場合に重ね合わせ部が設けられる．また，階段状 のみならず直線状に設置される例も見られる．しかしながら，GCL 重ね合わせ部や設置方法の違いが 堤体の安定性におよぼす影響は明らかでない．そこで本研究では，重ね合わせ部および直線状に設置 された GCL を有する堤高 3 m の堤体を対象に震動実験を行い，既往研究の連続かつ階段状に設置され た GCL を有する堤体との比較検討を行った．実験結果から，レベル2 地震動により，重ね合わせ部の 相対変位は発生しないことが明らかになった．さらに，クラック発生状況および堤体の変形状況から， 直線状よりも階段状に設置した堤体の方が耐震性が高いことが明らかになった．Recent years, Geosynthetic Clay Liners (GCLs) have been used to repair deteriorated small earth dams as impermeable materials. In a past study, the seismic performance of the embankment, in which a continuous GCL was installed in a stairs shape was verified. When retrofitting a embankment with GCL, GCL panel overlap can be introduced. In addition to a stairs shape, GCLs are used in a straight shape. However, the effects of GCL panel overlap and difference of installation methods on the seismic performance of the embankments remain unclear. In this study, full-scale shaking table tests were performed for 3 m embankment models with GCLs installed in a stairs shape and a straight shape, which were compared with the embankment with a continuous GCL in the past study. As a result, it was indicated that no change in GCL overlap length occurred due to shear displacement associated with Level2 shaking. Moreover, comparing the damage survey of embankments, it was revealed that the seismic performance of the straight shape is lower than that of the stairs shape. |
