Investigation into effects of past earthquake histories on liquefaction properties of dense sandy ground and seismic behavior of superstructures resting on it

2020 Fiscal Year Final Research Report

• Project/Area Number: 18H01531
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 22030:Geotechnical engineering-related
• Research Institution: The University of Tokyo
• Principal Investigator: Koseki Junichi 東京大学, 大学院工学系研究科(工学部), 教授 (30272511)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: 地盤工学 / 液状化 / 振動台実験 / 室内土質試験

Outline of Final Research Achievements

Experimental investigations were conducted to study the increase of the liquefaction resistance of sandy soil deposits that undergo gradual densification due to many earthquake histories as well as to reveal its effect on the seismic performance of superstructures resting on such dense sandy soil deposits.
As a result, the liquefaction properties of dense sands were found not simply to depend on their overall relative density. The structural performance was largely affected by the past shaking histories under otherwise similar conditions of the dense subsoils, including their overall relative density. It was also demonstrated that the liquefaction resistance of dense sands could be more significantly raised by applying partial liquefaction histories repeatedly.

Free Research Field

地盤工学

Academic Significance and Societal Importance of the Research Achievements

密な砂地盤の液状化特性が、平均的な相対密度だけでなく地震履歴の影響も受けることをを明らかにした点に学術的な意義がある。
実務においては密な砂地盤が重要構造物の支持地盤とされる場合が多いため、この研究成果は社会的にも意義も有する。
さらに、液状化しやすい砂地盤を締め固めて改良する際には、部分液状化履歴に相当する履歴を与えていくことで効果が高まると考えられることを示した点で、今後の応用研究の方向性も提示している。