Department of Civil and Environmental Engineering, College of Engineering (COE), A'Sharqiyah University (ASU), 400 Ibra, Oman.
School of Civil Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Pulau Pinang, Malaysia.
J Contam Hydrol. 2021 Mar;238:103769. doi: 10.1016/j.jconhyd.2021.103769. Epub 2021 Jan 9.
Laboratory-scale column experiments were carried out to assess the influence of water infiltration on pooled light non-aqueous phase liquid (LNAPL) redistribution in porous media. A simplified image analysis method (SIAM) was used to evaluate the saturation distributions of the LNAPL and water in the entire domain under dynamic conditions. The experiments were conducted for high/low LNAPL volumes LNAPL volumes differentiated as low and high volumes. High resolution SIAM images of the soil column during LNAPL migration and water infiltration events were captured and analyzed. Results indicated that the capillary fringe is about 6-7 cm which was consistent with the capillary height derived from empirical equations. Moreover, SIAM provided an estimate of the field capacity (30%) of the sand. Once the LNAPL infiltration stage was started, the LNAPL was observed to rapidly migrate through the vadose zone. For the case of large LNAPL volume, the LNAPL penetrated further into capillary fringe zone. Analysis of SIAM images showed that the LNAPL redistribution was observed to vary significantly with the rate of infiltration. For higher water infiltration intensity, the injected water exerted a larger hydrodynamic force on the entrapped LNAPL forcing it move further downward into the capillary zone and the saturated zone. Overall, this study demonstrated that the SIAM technique is an accurate and cost-effective tool for the visualization of the time-dependent NAPL/water movement in laboratory-scale experiments and dynamic changes in fluid saturation in porous media.
进行了实验室规模的柱实验，以评估水渗透对多孔介质中聚集的轻质非水相液体 (LNAPL) 再分布的影响。采用简化图像分析方法 (SIAM) 评估动态条件下整个域内 LNAPL 和水的饱和度分布。实验分为高/低 LNAPL 体积进行，低体积和高体积进行区分。在 LNAPL 迁移和水渗透事件期间，捕获并分析了土壤柱的高分辨率 SIAM 图像。结果表明，毛细带约为 6-7cm，与经验方程得出的毛细高度一致。此外，SIAM 提供了砂层田间持水量（30%）的估计值。一旦开始 LNAPL 渗透阶段，LNAPL 就会迅速穿过非饱和带。对于大体积 LNAPL 的情况，LNAPL 会进一步渗透到毛细带区。SIAM 图像分析表明，LNAPL 的再分布随渗透速率的变化而显著变化。对于更高的水渗透强度，注入水对被截留的 LNAPL 施加更大的水动力，迫使它进一步向下移动到毛细区和饱和区。总体而言，这项研究表明，SIAM 技术是一种用于可视化实验室规模实验中时变 NAPL/水运动和多孔介质中流体饱和度动态变化的准确且具有成本效益的工具。
