Clarification of mechanism of mud film formation focusing on microscale structural changes in soil pores during slurry infiltration

2024 Fiscal Year Final Research Report

• Project/Area Number: 23K13404
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 22030:Geotechnical engineering-related
• Research Institution: Hiroshima University (2024); Kyoto University (2023)
• Principal Investigator: Kido Ryunosuke 広島大学, 先進理工系科学研究科(工), 准教授 (40847365)
• Project Period (FY): 2023-04-01 – 2025-03-31
• Keywords: 安定液 / ベントナイト / 泥膜 / X線CT / 画像解析 / 浸潤

Outline of Final Research Achievements

The spatial distribution of bentonite within the pore spaces of sand was visualized after infiltration with bentonite-based and polymer-based stabilizing fluids, and the mechanism of mud film formation and the resulting changes in permeability were examined. It was found that higher bentonite concentrations, higher infiltration pressures, and smaller sand particle sizes led to more distinct mud film formation. In addition, bentonite tended to clog the pore spaces beneath the mud film, contributing to a reduction in permeability. In contrast, for polymer-based stabilizing fluids, no mud film was formed, and the reduction in permeability was attributed to the high viscosity of the stabilizing fluid.

Free Research Field

地盤工学

Academic Significance and Societal Importance of the Research Achievements

安定液浸潤時の泥膜形成については，基本的に土表面に形成される泥膜の目視や電子顕微鏡を用いた表面観察に留まっていた．これに対して本研究は，安定液浸潤試験にX線CTを適用する試験体系を新たに構築し，泥膜形成に加えてその下部にもベントナイトが局所的に目詰まりし透水性低下をもたらすことを明らかにしており，学術的な新規性の高い成果である．本研究の成果に基づき，安定液浸潤時の泥膜形成プロセスの予測法の開発につなげていく．これにより，泥膜が形成される条件が明確化され，アースドリル工法等での地盤掘削をより確実・安全に実施できるようになることが期待される．したがって本研究成果の社会的意義は大きい．