Study on mechanism of Oil contamination and remediation in the ground

通过平面应变条件下的模型试验和X射线计算机层析成像（CT）方法，研究了轻质非水相液体（LNAPL）在干/湿桑迪中的运移规律。为了评价桑迪中含水量或LNAPL的饱和度，提出了一种新的确定X射线CT图像阈值的方法。结果表明，桑迪的饱和度和颗粒特性改变了LNAPL的迁移机制，液体的分布形式因液体的S-p关系而异。饱和度大于20%的桑迪层对LNAPL的垂直入渗有抑制作用。在近地表滞留的水分比LNAPL多。在级配良好的材料中，LNAPL渗透在注入点周围发展。

The migration of Light Non-Aqueous Phase Liquid (LNAPL) in dry/wet sandy soils was visualized by the model tests in plane strain condition and using X-ray Computed Tomography (CT) method. To evaluate the saturation degree of water or LNAPL in the sandy soil, new method to decide the threshold value in X-ray CT image was proposed in this paper. It was concluded that saturation degree and grain property of sandy soil changed the migration mechanism of LNAPL, and the distribution form of liquids differed by S-p relation of liquids. Sandy soil layer with saturation degree at least more than 20% inhibited the vertical infiltration of LNAPL. More amount of water than LNAPL was retained in near-surface. LNAPL permeation developed around injection point in well graded materials.