愛媛大学農学部 地域防災学研究室
Laboratory of Engineering Mechanics for Disaster Prevention
Guraduate School of Agriculture, Ehime University
Research & Initiatives
現在取り組んでいる研究課題について紹介します．
The following is an introduction to the research projects we are currently working on.
水みちを探す
Measuring groundwater flow
地盤中を地下水が局所的に速く流れる水みちは，斜面災害を誘発します．そこで水みちを迅速に発見するため，地盤中に目印となる物質を井戸から流すトレーサ試験の研究を進めています．
Understanding groundwater flow in the ground is important for assessing the risk of landslides. We are conducting research on tracer testing to measure groundwater flow by flowing tracers into the ground from a well.
地盤の水の通りやすさを測る
Measuring the permeability of the ground
斜面災害にとって，地盤の水の通りやすさ（透水係数）を計測することは重要です．しかしながら，重い試験機器を斜面に持ち込むのは簡単ではありません．そこで，軽量で簡便なミニディスクインフィルトロメータという機器の活用を試みています．
Measuring the permeability of the ground is important for understanding landslides. However, it is not easy to carry heavy test equipment up a slope. We are therefore attempting to utilize a lightweight and simple device called mini disk infiltrometer.
物質の動きの基本を知る
Understanding the basics of behavior of contaminants.
地下水の流れによる物質の動きの基本を知るために，カラムという筒状の機器を使って実験を進めています．シンプルですが，本質を見抜くための強力なツールです．
To understand the basics of the movement of contaminants due to groundwater flow, we are conducting experiments using a cylindrical device called a column. It is a simple, yet powerful tool for seeing through to the essence of the matter.
フィンガー流を捉える
Cupturing free advection
地盤中に塩水が入ると，水よりも比重が大きいため，下に沈みます．この際，たくさんの指が伸びるような複雑な動き（フィンガー流）を示します．上の写真はガラス水槽と青色の色素を使って，その様子を捉えています．下の図は，画像解析によって写真を濃度分布に変換した結果です．（黄色の部分が濃度高い．）
When salt water enters soils or aquifers, it sinks because it has greater specific gravity than groundwater. In this case, it shows complex movements, such as the extension of many fingers (fingering). The upper photo captures the fingering using a transparent sand box and blue dye. The lower figure shows the result of converting the photo into a concentration distribution by image analysis (yellow areas are high concentration).
琉球石灰岩の間隙構造を調べる
Investigating pore structure of Ryukyu limestone
琉球石灰岩はサンゴ礁などが固まってできた岩石で，隙間がたくさんあり，地下水の貯留に有利です．そのため，地下に壁を作って地下水を貯める，地下ダムの貯留域に活用されています．しかしながら，地下ダムは地下水の流れをせき止めてしまうため，汚染物質の滞留が懸念されます．この汚染実態を解明するには，まず，琉球石灰岩内部における汚染物質の輸送特性を知ることが第一ステップとなります．輸送特性の基礎的な知見を得るため，X線CTを用いた間隙構造の評価を試みています．
Ryukyu limestone has many pore spaces, which are advantageous for groundwater storage. It is utilized in the reservoir area of subsurface dams that build an underground wall to store groundwater. However, subsurface dams can block groundwater flow, which can lead to the retention of contaminants. The first step in elucidating the mechanism of this contamination is to understand the transport characteristic of contaminants within Ryukyu limestone. We are attempting to evaluate the pore structure using X-ray CT to obtain fundamental knowledge of transport property.
