| 講演要旨(和文) | | 地中レーダーにより一般的な地表域で地下水関連情報が探査可能な手法として，時間シフト解析を適用した．水分率遷移領域の上昇により，遷移領域上部イベントの往復走時は短縮化し，下部イベントは長時間化することを数値計算で示した．実際の探査記録においても，同様な変化が確認された．本手法を用いることにより，擾乱物質が多くこれまで確認することができなかった地盤においても，水分遷移領域を捉えることができる可能性がある． |
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| | 講演要旨(英文) | | Ground-penetrating radar (GPR) can detect the distribution of volumetric water content under the ground. However, the level of water table in standard soil structures is difficult to be measured by using GPR. We evaluate time-shift analysis for time-lapse GPR records with different distribution of water content. The reflection events from the transition zone of water content are sometimes difficult to detect on the survey sections of GPR and also on the survey section subtracted from two time-lapse records. However, time-shift analysis can detect events caused by shift of the transition zone depth. Upper events of the transition zone move to in shallower record time and lower events move to in deeper time when watertable moves to a shallower area. We demonstrate such characteristic phenomena using FDTD numerical simulations and discuss the analysis results applied for time-lapse records acquired in actual fields. |
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