Unraveling the features of landslide movement and the advancement of risk assessment based on dense monitoring of groundwater veins

2022 Fiscal Year Final Research Report

• Project/Area Number: 19H02238
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 22030:Geotechnical engineering-related
• Research Institution: Toyama Prefectural University
• Principal Investigator: FURUYA Gen 富山県立大学, 工学部, 教授 (80378926)
• Co-Investigator(Kenkyū-buntansha): 王 功輝 京都大学, 防災研究所, 教授 (50372553) ; 渡部 直喜 新潟大学, 災害・復興科学研究所, 准教授 (60282977)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 地温計測 / 地すべり動態観測 / 物理探査 / 室内散水試験 / 地下水の押し出し現象 / 地すべり移動速度 / 効果判定

Outline of Final Research Achievements

We carried out monitoring of ground temperature, borehole water level, and groundwater dating to clarify the dynamics of flowing groundwater in the landslide mass. In addition, we attempted to replicate the moving velocity of landslide by the model based on the equation of motion combined with a damper (Lumped Mass Damper Model).
The results were shown that 1) the increase of groundwater (borehole water) level in the mass was not only caused by the process of ordinary rainfall seepage reaching the groundwater base level but also by pore air in the mass pushing out deep groundwater, 2) the above-mentioned model was able to replicate the moving landslide velocity in a simple manner, furthermore, was possible to determine the effect of countermeasures in a time-series basis.

Free Research Field

自然災害科学

Academic Significance and Societal Importance of the Research Achievements

学術的な意義は，地すべり滑動に関与する孔内水位（間隙水圧）の上昇が，従前からの降雨浸透過程の他に，詳細な地すべり土塊の地温変化の計測より，豪雨時の浸透過程で土塊内の間隙空気が深部地下水を押し出すことが判明した。ダンパーを組み合わせた運動モデルにより，地すべりの移動速度を時系列的に再現できたことである。
社会的意義は，斜面防災の観点から，前者の調査を斜面上で面的に展開することにより，効率的かつ効果的な地下水排除工の位置選定が大いに期待できること，後者の手法を対策工施工時に併用することにより，簡便かつ時々刻々と対策効果の評価が可能になることである。