2020 Fiscal Year Final Research Report

Practical study on rainfall water infiltration and slope failure mechanism in natural stratified slopes based on distributed sensor observations

Research Project

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Project/Area Number	18H01674
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	Gunma University
Principal Investigator	Wakai Akihiko 群馬大学, 大学院理工学府, 教授 (90292622)
Co-Investigator(Kenkyū-buntansha)	笹原克夫高知大学, 教育研究部自然科学系理工学部門, 教授 (90391622) Bhandary NetraPrakash 愛媛大学, 社会共創学部, 教授 (10363251) 蔡飛群馬大学, 大学院理工学府, 准教授 (20312902)
Project Period (FY)	2018-04-01 – 2021-03-31
Keywords	斜面 / 変形 / クリープ / 繰返し降雨 / 地すべり / 崩壊 / 構成則 / 有限要素法
Outline of Final Research Achievements	In this study, the attention was paid to the repeated rainfall conditions which follow the process such as rainfall, quiet period, and re-rainfall. In order to clarify the effect of rainfall on slope stability and its creep deformation, field observations, model experiments, and element tests were carried out. In addition to development a mechanical model to simulate characteristic phenomena that may be observed at an early stage before the slope failure, a few important findings related to the essence of such complicated phenomena relevant to rainfall-induced slope failures were obtained. Furthermore, a finite element code that implements the above model was developed and the possibility of applying it to the practice of disaster prevention was validated. The obtained results is an important clue to prevent slope disasters in the rainy season when rainfall continues intermittently, and contribute to the sophistication of warning and evacuation standard.
Free Research Field	地盤工学
Academic Significance and Societal Importance of the Research Achievements	本研究の学術的意義は，斜面変動のメカニズムを多面的に解釈した点にあり，成果は斜面変動予測の実務に資する。現地計測との連携などを通じて，急傾斜地対策工事における突発的な土砂災害の防止，あるいは，豪雨時や融雪時などに急速に速度を増加させる恐れのある地すべり運動の監視業務等において，現場技術者の適切な意思決定を支援することにもつながる。また，斜面近傍の住民や社会基盤施設の安全確保のための早期警戒避難の発令や降雨後の警報解除の適切な時期選定を考える上での基準雨量の高度化に資することが期待され，地球規模の気候変動に伴う今後の極端気象災害防止に向けた実践的な研究として，社会的意義も大きい。