難水溶性流体による地盤汚染とその浄化挙動の可視化

（Ｘ線CTスキャナを用いた間隙構造中の流体の可視化実験）

抄録

Non-aqueous phase liquids (NAPL) are immiscible materials and their flow behavior in the soil is multi-phase flow. In general, NAPL is categorized as contaminant fluid in the ground so it is important to study the contamination and remediation mechanism of NAPL in the ground. Micro focused X-ray computed tomography (CT) scanner is a powerful tool to observe inner condition of soil. The objective of this study was to understand the flow behavior of NAPL in soil. In this paper, experimental study was introduced to visualize the behavior of NAPL. In particular, it was explained that the study using X-ray CT to visualize the pore structure of sandy soil contaminated by light-NAPL (LNAPL) and remediated by flushing water and air. The result suggested that increase of the air flow rate did not attribute to reduce the volume of LNAPL blob in the range of capillary number which was defined as fingering phenomenon. However，different conditions of residual LNAPL blobs were found out significantly with increase of injection rates. The result of further image analysis, which could determine the number and size of blobs, indicated that it was caused by interaction of entrapment by wetting phase liquid and small pore.