摘要
文章通过室内试验研究层状非均质多孔介质中轻非水相液体(Light Non-Aqueous Phase Liquid,LNAPL)的运移机制与分布特性。首先,在二维砂槽上进行LNAPL的入渗试验,试验过程中用数码相机进行拍照,把LANPL的扩散过程以图像的形式记录下来;然后,用AutoCAD对图片进行分析处理,得出不同时刻LNAPL的入渗锋面变化图。结果发现,介质结构突变面改变了LNAPL的迁移模式。在LNAPL由中砂进入细砂层后,由于受到毛细作用的增强,其运移速度加快;而由中砂进入粗砂,受粗砂介质阻滞作用增强的影响,LNAPL运移速度变小。当LNAPL由干砂进入湿润砂体时,由于孔隙水浮托力增大,LNAPL先产生纵向运移,随后以横向迁移的形式在地下水位上部聚积。当达到一定厚度后,LNAPL的压头足以克服浮托力,驱替孔隙水进入砂土孔隙。另外,LNAPL的厚度足够大时,方可克服饱水层受到的浮托力,在地下水位上形成LNAPL池,并因孔隙水向周围砂体排泄,LNAPL池周围的水位上升。
Based on a laboratory experiment,migration mechanism and distribution characteristics of light non-aqueous phase liquid（LNAPL）in unsaturated layered heterogeneous porous media were studied.LNAPL infiltration experiment was done on a 2-D sand tank and pictures were taken to record the diffusion process by AutoCAD,after analyzing the pictures,the infiltration frontal variation pictures in different times were obtained.Result showed that migration model of LNAPL was changed with the structure face of media mutation.When LNAPL infiltrated into fine sand from medium sand,velocity of LNAPL infiltrating increased because of capillary pressure strengthen,and when LNAPL infiltrated into coarse sand from medium sand,velocity of LNAPL infiltrating decreased because of coarse sand block medium enhanced.When LNAPL infiltrated into wet sand from dry sand,LNAPL would make a longitudinal movement first,then accumulated in the top part of underground water with form of lateral movement.Once the accumulation of LNAPL reached to a certain thickness,pressure head of LNAPL could overcome buoyant force and drove out the water into sand.If accumulation of LNAPL is thick enough,it would overcome the buoyant force and LNAPL pool would be formed.Water inflow to the surround sand could make the level of surround water higher.
出处
《环境科学与技术》
CAS
CSCD
北大核心
2013年第1期31-34,83,共5页
Environmental Science & Technology
基金
国家自然科学基金(41102230)
广西自然科学基金(2011GXNSFB018004)
广西教育厅科研项目(200911LX128
201106LX229)
广西环境工程与保护评价重点实验室研究基金(桂科能0801Z007)
关键词
LNAPL
层状非均质
运移机制
分布特性
毛细作用
light non-aqueous phase liquid（LNAPL）
layered heterogeneous
migration mechanism
distribution characteristics
capillary
