Dynamic behavior of ground with inherent anisotropy and improvement of its prediction model

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K04598
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 22030:Geotechnical engineering-related
• Research Institution: Kyoto University
• Principal Investigator: Ueda Kyohei 京都大学, 防災研究所, 助教 (60649490)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 固有異方性 / 飽和砂地盤 / 液状化 / 遠心模型実験 / 中空ねじり試験 / 有効応力解析 / 構成モデル

Outline of Final Research Achievements

Shaking table tests in a centrifugal field and undrained cyclic shear tests using a hollow specimen were conducted to elucidate the dynamic behavior of ground with inherent anisotropy, as typified by liquefaction during earthquakes. The results demonstrate that the inherent anisotropy of the ground depending on the deposition angle affects not only the response during cyclic loading but also the behavior after vibration with the dissipation of excess pore water pressure. In order to predict the mechanical behavior of ground with inherent anisotropy precisely by numerical simulation, a constitutive model called the strain-space multiple shear mechanism model was validated. The results show that complex geotechnical behavior, in which anisotropy between principal strains and stresses becomes pronounced, can be elaborately represented by appropriately taking into account the influence of inherent anisotropy.

Free Research Field

地盤地震工学

Academic Significance and Societal Importance of the Research Achievements

我が国では南海トラフ地震や首都直下地震等の発生が切迫しており、液状化を始めとした地盤災害による被害形態や程度を高精度に予測する技術の確立が急務である。地盤は堆積環境等に起因した固有異方性を有しているのが一般的であるが、これまで地震時における動的応答の評価の際に、固有異方性の影響が考慮されることはほとんどなかった。本研究における遠心模型実験と室内土質試験により、地盤の動的挙動が固有異方性の影響を強く受けること、および適切な土の構成モデルを用いることでこのような固有異方性の影響を数値シミュレーションにより考慮できることが示された。これにより今後の地盤災害の予測精度の向上につながるものと考えられる。