Shallow landslide mechanism due to the heavy rainfall after the large-scale earthquake based on the evaluation of foundation strength and permeability on a mountainous area

2020 Fiscal Year Final Research Report

• Project/Area Number: 18K04669
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 25030:Disaster prevention engineering-related
• Research Institution: Ritsumeikan University
• Principal Investigator: Fujimoto Masamitsu 立命館大学, 理工学部, 准教授 (60511508)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: 大規模地震 / 地盤強度 / 斜面崩壊 / 降雨浸透特性 / 豪雨

Outline of Final Research Achievements

During the heavy rainfall after large-scale earthquakes, previous studies reported that the numbers of new shallow landslide increased, and the enlargement of past shallow landslide occurred. To understand such phenomena, there is a need to evaluate the change of foundation strength and structure by the crack, and permeability change with above foundation change. In this study, shallow landslides were reproduced by adding the vibration and artificial rainfall at the laboratory experiment. Also, to evaluate the inside condition of crack, the experiments with artificial crack condition were conducted. As a result, after the vibration the change of permeability of slope soil lead to changes of groundwater movement and also soil strength, suggesting that such changes are one of the factors of instability of slope.

Free Research Field

防災工学

Academic Significance and Societal Importance of the Research Achievements

大地震後に豪雨が発生した場合、豪雨による土砂災害に比べて被害が大きくなることが報告されている。この現象を解明するためには、地震後の亀裂による内部構造の変化や強度低下とそれらに伴う降雨浸透特性の変化の把握が必要である。本課題では，室内斜面実験によって検証した結果，地震後には土壌の浸透性が変化し、地下水位の変動に差が生じること、また、土壌の強度が低下する場所が確認され、斜面の不安定化する原因が明らかになった。