Elucidation of the mechanical effects of snow on landslide movements - Toward the establishment of "Cryospheric Landslide Science"

2021 Fiscal Year Final Research Report

• Project/Area Number: 19H03009
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 40010:Forest science-related
• Research Institution: Forest Research and Management Organization
• Principal Investigator: Okamoto Takashi 国立研究開発法人森林研究・整備機構, 森林総合研究所, 主任研究員 等 (30353626)
• Co-Investigator(Kenkyū-buntansha): 松浦 純生 京都大学, 防災研究所, 名誉教授 (10353856) ; 竹内 由香里 国立研究開発法人森林研究・整備機構, 森林総合研究所, 主任研究員 等 (90353755) ; 平島 寛行 国立研究開発法人防災科学技術研究所, 雪氷防災研究部門, 主任研究員 (00425513) ; 村上 亘 国立研究開発法人森林研究・整備機構, 森林総合研究所, 主任研究員 等 (10353880)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 地すべり / 積雪 / せん断強度 / 斜面安定解析

Outline of Final Research Achievements

In order to elucidate the unusual landslide mechanism that slows down the landslide activity during the snowy season, we investigated the effect of the mechanical action of the snowpack layer on the landslide activity through field measurements and numerical analysis. The average shear strength of the snowpack was 7.9 kN/m^2, which tended to increase with depth due to snow consolidation and refreezing. Slope stability analysis using the topographic and geologic characteristics of the landslide and the obtained snowpack parameters indicated that loading of the snowpack increased the slope safety factor by 13.5%. The shear strength of the snow cover layer in particular contributed strongly to this increase. In conclusion, we obtained reasonable results on the mechanism of the slowdown of landslide activity during the snow season.

Free Research Field

治山工学

Academic Significance and Societal Importance of the Research Achievements

積雪地域の地すべりの一部は、地下水位が高い融雪期にも活動が鈍い事例が散見されるため、同時期の正確な危険度評価を困難にしていた。本研究成果で得られた積雪の力学的作用を考慮することで、融雪期をはじめとする積雪期の地すべり危険度の正確な評価に貢献でき、ひいては積雪地域の地すべり警戒・避難態勢の構築に寄与できると期待される。