Cause investigation of damage in pile foundation during the 2016 Kumamoto Earthquake and improvement of response analysis method of pile foundation against inland earthquakes

2018 Fiscal Year Final Research Report

• Project/Area Number: 17H06837
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Single-year Grants
• Research Field: Building structures/Materials
• Research Institution: Osaka University
• Principal Investigator: Nakano Takaharu 大阪大学, 工学研究科, 助教 (00805806)
• Research Collaborator: MIYAMOTO Yuji
• Project Period (FY): 2017-08-25 – 2019-03-31
• Keywords: 2016年熊本地震 / 杭基礎建物 / 非線形相互作用 / 地盤調査 / 凝灰質粘性土 / 杭－地盤間の剥離 / 有限要素法 / 質点系モデル

Outline of Final Research Achievements

This study aims to investigate factors of soil-structure interaction and pile damage of Mashiki Town Office during the 2016 Kumamoto Earthquake. The town office was subjected to strong motions twice. The investigation was based on in-situ ground survey, experiment, and analyses. For the response analysis of the town office, nonlinearity of volcanic clayey soil (i.e. strong motion amplification and nonlinearity of subgrade reaction) and continuous input motion were considered. As a result, calculated acceleration response of the first floor was good agreement with observed one. The analytical result also showed that factors of soil-structure interaction influenced seismic response and pile damage of the town office.

Free Research Field

建築構造

Academic Significance and Societal Importance of the Research Achievements

平成28年熊本地震は、建物内（益城町庁舎）と近隣の地盤（KiK-net益城地点）で非常に強い揺れが同時に、それも複数回にわたり観測された稀有な事例である。特に建物内で得られた観測記録は、地盤－構造物系の非線形相互作用の影響を受けたものである。本研究成果は、内陸直下地震下の軟弱な粘性土地盤における非線形相互作用を観測記録と解析に基づいて説明したものであり、同現象の理解とモデル化に関する有用な知見を与えたと考えられる。