Development of numerical techniques for wave propagation and scattering in seabed layer including methane-hydrate bearing sediment and its application to geophysical exploration

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K18137
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Structural engineering/Earthquake engineering/Maintenance management engineering
• Research Institution: Tokyo Institute of Technology
• Principal Investigator: Furukawa Akira 東京工業大学, 環境・社会理工学院, 助教 (60724614)
• Research Collaborator: Hirose Sohichi ; Saitoh Takahiro
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: メタンハイドレート / 凍結した多孔質体 / 波動解析 / 境界要素法 / アンセンテッドカルマンフィルタ / 形状推定

Outline of Final Research Achievements

This research studies wave analysis of seabed layer including methane-hydrate bearing sediment. We use frozen porous media for modeling the dynamic behavior of the seabed layer. Using the frozen porous media, we can explicitly express the volume ratio of the hydrate sediment. We develop frequency-domain and time-domain boundary element methods (BEMs) for wave scattering in frozen porous media. In time-domain analysis, convolution quadrature method is used for temporal discretization. Some numerical results present the validity of our proposed BEMs. We also develop an estimation method for the shape of methane-hydrate bearing sediment in seabed layer. In this approach, we try to estimate some parameters of the shape of the sediment using the properties of the scattering waves. We show the validity of our estimation method by solving some typical problems.

Free Research Field

工学

Academic Significance and Societal Importance of the Research Achievements

本研究では，凍結した多孔質体の波動問題に対する順解析手法および逆解析手法の開発を行なっているが，この力学モデルに対する波動解析の研究例は世界的にも珍しく，学術的意義を有していると考えられる．さらに，凍結した多孔質体を用いることによりハイドレート堆積物の体積割合を明確に表現した上で解析を実現することができる点も，今後の探査技術の発展に貢献できる可能性を有している．