2022 Fiscal Year Final Research Report

Development and validation of a damage prediction method for reliquefaction taking into consideration the variation in induced anisotropy during liquefaction

Research Project

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Project/Area Number	19H02402
Research Category	Grant-in-Aid for Scientific Research (B)
Allocation Type	Single-year Grants
Section	一般
Review Section	Basic Section 25030:Disaster prevention engineering-related
Research Institution	Tohoku University
Principal Investigator	Yamada Shotaro 東北大学, 工学研究科, 准教授 (70346815)
Co-Investigator(Kenkyū-buntansha)	京谷孝史東北大学, 工学研究科, 教授 (00186347) 中野正樹名古屋大学, 工学研究科, 教授 (00252263) 淺岡顕公益財団法人地震予知総合研究振興会, 地震防災調査研究部, 副首席主任研究員 (50093175) 野田利弘名古屋大学, 工学研究科, 教授 (80262872)
Project Period (FY)	2019-04-01 – 2022-03-31
Keywords	液状化 / 再液状化 / 水～土連成解析 / 弾塑性 / 動的解析 / 誘導異方性
Outline of Final Research Achievements	Based on laboratory element experiments, it was revealed that a systematic change in induced anisotropy occurs during liquefaction and that the state of anisotropy at the end of liquefaction significantly affects the re-liquefaction resistance. To numerically reproduce such liquefaction and re-liquefaction behavior of sandy soils, we proposed the combined loading elasto-plastic constitutive equation that integrates the SYS Cam-clay model and the Drucker-Prager model. The model is implemented in a dynamic soil-water coupled analysis code and is shown to explain various characteristics of liquefaction and re-liquefaction phenomena. Furthermore, this study demonstrated that the liquefaction countermeasures using the permeation grouting method could be evaluated based on the developed analysis theory.
Free Research Field	土木工学
Academic Significance and Societal Importance of the Research Achievements	液状化被害を受けた地区に住む人々は，またいつ訪れるかわからない地震による再液状化被害に常に不安を憶えながら生活を営んでいる．また，当該地区は人口流出現象にも直面している．これらの不安を軽減するために様々な液状化対策工法が提案されているが，その効果を定量的に予測するのは難しい．本研究では，誘導異方性に着目して再液状化現象の主要なメカニズムを明らかにするとともに，砂質土の誘導異方性の変化を考慮可能な数理モデルを開発した．さらには，提案モデルを水～土連成解析コードに実装し，液状化対策効果の評価に適用可能であることを例証した．