Seismic evaluation of linear civil engineering structures by surface waves excited in the Osaka Plain

2020 Fiscal Year Final Research Report

• Project/Area Number: 17K06533
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Structural engineering/Earthquake engineering/Maintenance management engineering
• Research Institution: Kobe University
• Principal Investigator: Kuwata Yasuko 神戸大学, 工学研究科, 准教授 (50379335)
• Project Period (FY): 2017-04-01 – 2021-03-31
• Keywords: 大阪平野 / 地震観測 / 地盤ひずみ / 表面波 / 埋設管

Outline of Final Research Achievements

In this study, in order to clarify the seismic characteristics of surface waves excited in the Osaka Plain, three seismographs were near the seismograph in Fukushima-ku, Osaka City and continuous observation was started for 24 hours since October 2017. The seismic ground motions were observed with all the seismographs in the 2018 northern Osaka earthquake and the 2021 earthquake off Fukushima. In the earthquake in the northern Osaka Prefecture, the seismographs are located in the southwest direction from the epicenter, but surface waves arrived from a direction slightly east of the epicenter, and are strongly influenced by the Uemachi fault zone running north and south on the east side. Furthermore, it was found that the ground strain due to surface waves is almost the same as the that due to body waves.

Free Research Field

地震工学

Academic Significance and Societal Importance of the Research Achievements

日本のガスや水道、下水道などの埋設管路の耐震基準を横断的に見れば、地震波動による埋設管の影響評価に用いる地盤ひずみの算出過程において、想定している地震波動は実体波や表面波で統一性がなく、波の伝播速度も指針によって異なる。表面波が励起されやすい平野においては、地震時には表面波による地盤ひずみは無視できないと考えられるが、本研究で行った地震観測によって表面波に起因する地盤ひずみの特徴を踏まえることができた。