A New Method for Slope Failure Prediction Based on Microscopic Approach Considering Piping Phenomena

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K04263
• 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: Tokuyama College of Technology
• Principal Investigator: Araki Kohei 徳山工業高等専門学校, 土木建築工学科, 准教授 (00600339)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: パイピング / 土砂災害 / 斜面崩壊 / 不飽和土 / 粘着力 / 間隙比 / 飽和度 / 崩壊確率

Outline of Final Research Achievements

To develop a community-based sediment hazard prediction system, we focused on the phenomenon of piping and attempted to construct an analytical method based on a mechanical approach and a probabilistic method. The assumption is that the slope safety factor is smaller for dense sand with a small pore ratio because of the increase in the self-weight of the soil mass. However, in model experiments, loose packed soil above the slip surface is more likely to cause slip and collapse. To evaluate this, the pore ratio change associated with piping was related to the cohesion of unsaturated soil. The results indicate that the slope failure probability increases with increasing pore ratio and saturation. The increase in subsurface infiltration flow with precipitation revealed that piping occurs through a cyclic development of fine-grained runoff, an increase in mean pore size, and an increase in infiltration flow rate.

Free Research Field

地盤工学

Academic Significance and Societal Importance of the Research Achievements

本研究では，経験的な方式を用いて，パイピング現象を考慮した斜面崩壊予知手法を検討しているが，間隙比や土中水分だけでなく，均等係数や平均粒径といった土質パラメータを関連付け，種々の現象を説明・解析するための新たな土の力学モデルを作成し，経験則に頼らない手法を開発していく必要がある．これによりはじめて，経験したことのない災害等を予知できるようになり，気候変動等への対応を可能にしていくことができる．並行して，地理情報システムを用いた地理的評価を行い，経時的な斜面崩壊危険度の把握を行っていくことで有用性が示されていくと期待できる．