| 講演要旨(和文) | | 斜面災害の防災の観点から，斜面内に浸透した水分の時間変化を空間的に把握することが重要とされている．本研究では，防災科学技術研究所の大型降雨実験施設内に作成された盛土において，2011年2月から約1か月おきに2年間の比抵抗法電気探査の繰り返し測定を行ってきた．これまでの測定から，盛土中の比抵抗は湿潤な夏季に低くなり，乾燥する冬季に高くなるという季節変化が明瞭にとらえられた．しかし，比抵抗の長期的な変化は温度変化の影響が大きいことも明らかになり，比抵抗変化から水分変化を推定するためには温度補正が必要であると考えられた．そこで，盛土から採取した土壌サンプルの比抵抗の温度依存性を計測した．その結果，比抵抗と温度の間の線形関係式が求められた．その式を用いて比抵抗に温度補正をしたところ，比抵抗と水分との関連性が明瞭となり，斜面内の長期の水分変化の推定に比抵抗モニタリングが有効であることが示された． |
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| | 講演要旨(英文) | | From a viewpoint of prevention of a slope disaster, it is important to detect the time change of water content in the slope spatially. We have conducted repeated monthly resistivity surveys for two years since February, 2011, on the slope of an embankment in the large-scale rainfall simulator of the National Research Institute for Earth Science and Disaster Prevention (NIED). The results clearly show seasonal changes in the resistivity structure of the embankment, with resistivity becoming low in the summer wet season and high in the winter dry season. It is obvious that the long-term resistivity change is greatly affected by the temperature change. This means that the temperature correction to resistivity is required in order to estimate the water content change from the resistivity change. Therefore we measured the temperature dependency of the resistivity of the soil samples extracted from the embankment. As a result, the empirical formula of the linear relation between resistivity and temperature was acquired. We confirmed that the resistivity corrected using the formula have a linear relation to the water content. This indicates that resistivity monitoring is effective for monitoring changes in water content in the slope of an embankment. |
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