波浪―地盤―洋上モノパイルの相互作用に関するドラム遠心実験  [in Japanese] DRUM CENTRIFUGE TESTS ON WAVE-SEABED-OFFSHORE MONOPILE INTERACTION  [in Japanese]

Access this Article

Author(s)

Abstract

本研究では,高波作用時の洋上風力発電基礎モノパイルの安定性検討の観点から,砂地盤-モノパイル系の一連の波浪実験を行い,波による液状化にともなうモノパイルの不安定化過程を詳しく調べている.実験は遠心力場70gで行った.実験の結果,液状化の進展とモノパイルの不安定化とは密接に関係することが得られた.すなわち,根入れ長さDの1/3程度が液状化すると,パイプが揺動しはじめ,その後の液状化領域の拡大にともないパイルが倒壊に至ることが得られた.さらに,モノパイルを密な支持層へ適切な深さ(D/2)まで根入れしておくことで,波の液状化に伴うパイルの残留変位の発達が抑えられることや,モノパイルが地盤中に存在することで,液状化抵抗が増大することが得られ,進行波載荷に伴う主応力軸回転の重要性を示した.

 This paper discusses the experimental findings pertaining to the instability of the offshore monopile foundations due to wave-induced liquefaction in sand beds. The emphasis of the experiments was placed on investigating the relation between the occurrence/propagation of liquefaction and the increase in the displacement of the monopile, leading to collapse under the action of severe traveling fluid waves. A range of wave tests using a drum centrifuge was performed under a centrifugal acceleration of 70 gravities. It was found that the monopile put on the bed base started moving significantly upon the progress of liquefaction to the soil depth corresponding to the 1/3 of embedment depth of the monopile. The experimental results also show the effects of embedment to the dense layer and the significance of rotation of principal stress axes.

Journal

  • Journal of Japan Society of Civil Engineers, Ser. B3 (Ocean Engineering)

    Journal of Japan Society of Civil Engineers, Ser. B3 (Ocean Engineering) 74(2), I_856-I_861, 2018

    Japan Society of Civil Engineers

Codes

Page Top