Advanced Subsurface Structure Estimation Based on 6-Component Deployment Array Observations of Microtremors

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K04575
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 22020:Structure engineering and earthquake engineering-related
• Research Institution: University of Fukui
• Principal Investigator: Kojima Keisuke 福井大学, 学術研究院工学系部門, 教授 (40205381)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 地盤震動 / 並進・回転成分 / 表面波 / 位相速度 / 地下構造 / 逆解析

Outline of Final Research Achievements

In this study, we proposed a method of utilizing six-component vibration observation information by adding three rotational components to three translational components. This method eliminates the need for simultaneous observation by multiple vibration pickups, which is indispensable for conventional translational component observation. The proposed method can evaluate the direction of arrival, the amplitude of each component of the surface wave, and the propagation velocity of the surface wave from the six-component observation information.In order to apply the proposed method in practice, the performance of a newly developed three-component rotational velocity sensor has been checked and its usefulness confirmed. In addition, we applied the proposed method to field experiments using a shaker and strong-motion observation data. The results show that the phase velocity of Rayleigh waves can be estimated with high accuracy.

Free Research Field

地震防災

Academic Significance and Societal Importance of the Research Achievements

従来の振動計測による地下構造探査法では，多数のピックアップを一列あるいは同一円周上に配置した同時観測を多重に行うことが求められ，その時間・人的・金銭的コストが高いことから，実施地点が限られ，結果として，信頼性の低い地下構造モデルによる地震被害予測などが行われることに繋がっていた．本研究では，従来の並進３成分に，三軸周りの回転成分を同時に観測し，その分析を行うことにより，信頼性と精度の高い表面波伝播特性および地下構造の推定を実現する．福井県各地の平野域で詳密な観測と分析を実施し，従来のデータベースとあわせることにより，信頼性の高い地下構造モデルを提示することが可能となる．