Development of Evaluation Method for Holding Power of Suction Anchor for Deepwater Mooring

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K14884
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Naval and maritime engineering
• Research Institution: The University of Tokyo (2018-2019); Kyushu University (2017)
• Principal Investigator: Toh Kimihiro 東京大学, 大学院新領域創成科学研究科, 助教 (80790716)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 把駐力評価 / サクションアンカー / 数値シミュレーション / 個別要素法 / 簡易評価式

Outline of Final Research Achievements

In this study, some coupled analyses between soil and anchor structures were performed using the ALE (Arbitrary Lagrangian Eulerian) function implemented in the general-purpose nonlinear finite element analysis software, LS-DYNA, as well as a numerical simulation based on the in-house code of the DEM (Distinct Element Method) to predict a holding power of suction anchors.
In addition, basic laboratory experiments and a simplified evaluation formula based on the two-dimensional Rankine’s earth pressure theory regarding the holding power of suction anchors were investigated.
As a result, it was confirmed that a qualitative tendency of the maximum holding power might be assessed by the simplified evaluation formula as for some collapse modes of soil. More investigation about the comprehensive simplified evaluation formula is one of the future works.

Free Research Field

船舶海洋工学

Academic Significance and Societal Importance of the Research Achievements

本研究では，海洋資源開発の際の要素技術の1つとなりうるアンカーの把駐力について検討を行った．
これまでに実績の多い欧米の粘土質地盤に対し，日本周辺海域に多い砂質地盤に対する適用例は稀だと言える．そこで，数値シミュレーションによる砂質を想定した土壌・アンカー間の連成解析に加え，解析的なアプローチに基づく簡易的な把駐力評価手法に関する検討を行った．
その結果，評価式には改善の余地が認められたが，土壌の崩壊モードによっては，その定性的な傾向を捉えられているところもあり，本研究により得られた知見をさらに発展させることで，定量的な評価手法の確立が望まれる．