Evaluation of flow behavior of sediment gravity flow

2020 Fiscal Year Final Research Report

• Project/Area Number: 18H01295
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 17040:Solid earth sciences-related
• Research Institution: Hokkaido University
• Principal Investigator: Kameda Jun 北海道大学, 理学研究院, 准教授 (40568713)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: 北海道胆振東部地震 / 斜面崩壊 / 流動化地すべり / ハロイサイト / ゼータ電位 / 細胞外ポリマー

Outline of Final Research Achievements

The Eastern Iburi earthquake (Mw = 6.7) occurred on 6 September 2018 in southern Hokkaido. The resulting strong ground motion caused hill slopes widely covered by volcanic soils near the epicenter to fail suddenly. In this study, we investigated the mechanism of landslide initiation and runout behavior, paying particular attention to the surface properties of soil particles. Field surveys revealed that, in most of these landslides, the basal part of the volcanic soils acted as the principal slip surface, where halloysite clay minerals were specifically formed. Halloysite is spherical to irregular in shape, has high water retention and absorption properties, and the particle surface is negatively charged in a wide pH range. These properties may have contributed to the instability of slopes and the high mobility of soils during the earthquake.

Free Research Field

構造地質学

Academic Significance and Societal Importance of the Research Achievements

2018年北海道胆振東部地震が発生した際に、震源付近の火山灰土壌で覆われた斜面が大規模に崩壊し、大きな被害がもたらされた。日本は火山国であり、今回崩壊したような火山灰土壌は全国に広く分布する。今回の研究により、火山灰土壌の崩壊・流動現象が、ハロイサイト粘土鉱物の形状や表面物性と密接に関係していることが明らかとなった。土壌中のハロイサイト粘土鉱物の分布に加えその性状を把握することは、火山地帯における斜面災害対策を講じる上で重要と考えられる。