Development of mixed fine particles injection method as a liquefaction countermeasure

2021 Fiscal Year Final Research Report

• Project/Area Number: 19H02240
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 22030:Geotechnical engineering-related
• Research Institution: Tokyo City University
• Principal Investigator: SUEMASA NAOAKI 東京都市大学, 建築都市デザイン学部, 教授 (80206383)
• Co-Investigator(Kenkyū-buntansha): 伊藤 和也 東京都市大学, 建築都市デザイン学部, 教授 (80371095) ; 田中 剛 東京都市大学, 建築都市デザイン学部, その他 (80468818)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 地盤改良工法 / 液状化対策 / 微粒子 / 浸透注入 / 固化

Outline of Final Research Achievements

The purpose of this research is to develop a fine particle injection method to inject multiple solids with a small particle size into the ground with water in the sand ground where liquefaction is a concern. After injection, these materials react and solidify with the surrounding sand particles.
From the materials that can be made into fine particles at low cost, combinations that are expected to have high strength after solidification were extracted. As a result, the combination of blast furnace slag, hemihydrate gypsum, and magnesium oxide fine particles satisfied sufficient compressive strength. In the ground injection, the higher the concentration of fine particles, the easier it is to clog, and it is necessary to inject a solution with a water powder ratio (weight) of about 6 to 10% at a high flow velocity. In the fine particle infiltration experiment using the two-dimensional model soil layer, the mixed fine particles were injected as a plan and solidified in a few weeks.

Free Research Field

地盤工学

Academic Significance and Societal Importance of the Research Achievements

既設構造物に対する既存の液状化対策は高額で，狭隘地での施工が難しいという欠点があった．そこで，安価な材料の中から施工性が良い微粒子粉体による浸透注入型の液状化対策工法を開発した．地盤に対してスラリーを攪拌混合するものや液体を浸透注入させる工法は多くあるが，固体を浸透注入させる方法は極めて斬新である．材料の垂れ下がりがないことから施工は容易であり，改良強度も非常に高い．今後，地域地盤の性質に応じて微粒子の組合せを変更することにより，材料費がより廉価になる可能性もある．