A proposal of the dynamic property estimation technique of the deep and shallow ground for a building foundation design

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K04705
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 23010:Building structures and materials-related
• Research Institution: Yamagata University
• Principal Investigator: MITSUJI Kazuya 山形大学, 工学部, 教授 (90292250)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 建築基礎構造 / 常時微動観測 / 小規模建築 / 深部地盤 / 浅層地盤 / 動的特性 / 地盤特性 / 山形盆地

Outline of Final Research Achievements

Attempt to propose the dynamic estimation technique of the deep and shallow ground for advanced building foundation design by microtremor measurement and seismic observation data. Predominant frequencies of the ground at many sites in Yamagata basin were quantitatively estimated. Results pointed out that estimated predominant frequency by microtremor measurement is significantly different from geomorphic classification, and the effect of the deep ground was observed in H/V spectral ratio of some sites. The estimation of the dynamic characteristics of the shallow layer was also attempted to develop by cross correlation function of microtremor data for a small building foundation design. Results tends to indicate the predominant frequency appears in high frequency range, and its accuracy needs to be improved in the near future. However, the availability of this technique can be shown in this research project.

Free Research Field

建築基礎構造

Academic Significance and Societal Importance of the Research Achievements

場所による揺れ方の違いを比較的簡便な観測手法で定量的に評価することは建築設計の面からも防災の面からも有用である。内陸の活断層の存在が指摘される山形盆地で高密度に常時微動観測を行い、面的な場所による揺れ方の違いや微地形区分からの推定値との差を評価したほか、深い地盤構造の影響が地表面の揺れに影響を与えることや、小規模建築を念頭に浅層地盤を伝わる波の特性か地盤の「かたさ」を評価する手法を検討した。結果の精度面ではまだまだ改良の余地があるが、建築基礎構造設計に有用な情報を提供できる手法となりうることを示した。