2021 Fiscal Year Final Research Report

Clarification of Reinforcement Effects and Limitations of Vegetation Works in Cold Regions

Research Project

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Project/Area Number	19K04591
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	Kitami Institute of Technology
Principal Investigator	NAKAMURA Dai 北見工業大学, 工学部, 准教授 (90301978)
Co-Investigator(Kenkyū-buntansha)	川口貴之北見工業大学, 工学部, 教授 (20310964) 川尻峻三北見工業大学, 工学部, 准教授 (80621680) 宗岡寿美帯広畜産大学, 畜産学部, 教授 (50301974)
Project Period (FY)	2019-04-01 – 2022-03-31
Keywords	緑化工学 / 植生工 / 植物根系 / 補強効果 / 風化抑制効果 / せん断抵抗 / 侵食抵抗 / 凍結融解
Outline of Final Research Achievements	In this study, we attempted to clarify the three reinforcement effects expected from vegetation works (i.e., prevention of surface failure, prevention of erosion by rainwater, and prevention of weathering of the cut slope). Constant-pressure one-surface shear tests revealed that the shear resistance increased with a specimen with a well-developed root system. It was also found that the effect of freeze-thaw history on shear strength was small. Furthermore, the erosion resistance tests revealed that the erosion resistance was increased by the root system, stems and leaves of the plants, and that the erosion depth was decreased. However, erosion resistance was found to be reduced by freeze-thaw history. Finally, in-situ measurements indicated that the vegetation works had little effect on the weathering of cut slopes in areas with little snowfall and cold temperatures.
Free Research Field	地盤工学
Academic Significance and Societal Importance of the Research Achievements	植生工の効果や機能を定量的に評価する手法は確立されておらず，特に草本植物については，植物の種類や成長の度合いといった要素で評価された調査データや研究成果は極端に少ない。本研究では植生工の補強効果について，植物根系の発達状況との関係から評価することに取り組んだ。加えて，凍結融解履歴が植生工に与える影響についても検討を行った。このような研究事例は国内外に関わらず存在しておらず，他に類を見ない。また，植生工に期待される3つの補強効果を網羅的に解明した研究事例は皆無であり，本研究で得られた成果は将来的に道路土工指針や河川堤防設計指針に反映され，周辺地域の地盤・河川防災に貢献できると考えられる。