Challenge to Ultra-efficient and Accurate Evaluation of Infiltration and Strength Properties of Unsaturated Soil Using Continuous Pressurized method

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K18752
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 22:Civil engineering and related fields
• Research Institution: Kyushu University
• Principal Investigator: Yasufuku Noriyuki 九州大学, 工学研究院, 教授 (20166523)
• Project Period (FY): 2021-07-09 – 2024-03-31
• Keywords: 不飽和土 / 水分特性曲線 / 不飽和透水係数 / 一面せん断強さ / 吸排水履歴とせん断強さ / 連続加圧型保水試験 / ハイブリッド形式

Outline of Final Research Achievements

This study utilized the continuous pressurization method to develop a new hybrid system that allows concurrent determination for the hydraulic conductivity function (HCF) and the soil water characteristics curve (SWCC). The system is hybridized by linking it to three cells for direct shear box testing, allowing the testing of the tested specimens to be set at designated hydrological conditions simultaneously. The system enables the SWCC, HCF, and shear strength of sandy soil specimens linked to each other to be determined. The efficiency and accuracy compared with conventional methods were confirmed and served as a tool that can be used reliably in practice. A series of tests using this system showed that the relationship between shear strength and water absorption/drainage history can be clarified efficiently.

Free Research Field

地盤工学

Academic Significance and Societal Importance of the Research Achievements

不飽和土の浸透特性値と強度定数がワンステップで所定の精度の下で迅速かつ同時に得られれば、斜面や河川堤防における地質・地盤リスクを分析する精度は飛躍的に向上する。本研究は、このような認識から、①水分特性曲線と連動させて、透水係数と強度定数をワンステップで求めるための方法論を明らかにし、②水分特性曲線と透水係数をそれぞれ得るのに従前の概ね20分の1の時間で測定できる画期的なシステムを利用者の視点から構築したものである。圧倒的な効率化と高精度化の結果として、当該試験の生産性を格段に向上させるだけではなく、現状の測定システムの体系や方向性を変革する可能性を秘めており、学術的・社会的意義は大きい。