Development of integrated seismic estimation technology for failure and deformation due to liquefaction during earthquakes in agricultural small pond

2018 Fiscal Year Final Research Report

• Project/Area Number: 16H04994
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Rural environmental engineering/Planning
• Research Institution: Ibaraki University
• Principal Investigator: MOHRI Yoshiyuki 茨城大学, 農学部, 教授 (90373224)
• Co-Investigator(Kenkyū-buntansha): 河端 俊典 神戸大学, 農学研究科, 教授 (20335425)
• Research Collaborator: TAGASHIRA HIDEKAZU ; IZUMI AKIRA
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: ため池 / 耐震診断 / 土の強度と変形 / 土の劣化と強度低下 / すべり破壊 / 超大ひずみ / 累積損傷

Outline of Final Research Achievements

We developed a ring shear test apparatus that can clarify the deformation and strength deterioration characteristics up to very large strain, and based on the test results, we developed a "generalized standard strength reduction model" that can be applied to the pond embankment soil. The model considering strength reduction due to this cumulative damage was introduced to the finite element method analysis, and the earthquake behavior of the embankment and its residual deformation prediction simulation were carried out. The simulation well predicts the results of seismic response behavior, progressive failure mode and residual deformation of the embankment obtained by the model tests of the pond embankment using a centrifugal loading device. Therefore, it has been confirmed that the generalized standard strength reduction model and finite element analysis using this model, plastic slip analysis have high applicability as an integrated seismic diagnostic system.

Free Research Field

農業工学

Academic Significance and Societal Importance of the Research Achievements

現在，ため池などの土構造物の地震時の決壊の危険性を定量的に評価できる手法はない。
本研究の成果である堤体の超大ひずみレベルまでの強度低下特性モデル「一般化標準強度低下モデル」をプロトタイプとして，塑性すべり解析や有限要素法解析に導入することによって、初期の微小変形からすべり破壊，堤体の決壊にいたる大規模崩壊（決壊）を統一的に評価することが可能となる。すなわち，決壊可能性の高いため池を定量的に峻別することができ，社会的な意義は極めて高い。さらに，数百％を越える超大ひずみまでの広範囲の強度低下のモデル化は，すべての土構造物に共通の課題であり，学術的意義も高い。