بررسی پارامتریک توابع نگهداشت خاک در سیستم دو فازی LNAPL- هوا

نوع مقاله: مقاله پژوهشی

چکیده

به منظور بررسی رفتار هیدرولیکی LNAPL  ها در خاک، منحنی­های نگهداشت خاک برای بنزین و آب به­وسیله­ی دستگاه ستون آویزان بدست آمد. سپس، هدایت ­هیدرولیکی اشباع خاک برای سیالات بنزین و آب به­ روش بار ثابت تعیین شد. پارامترهای منحنی­های نگهداشت ­خاک، برای آب و بنزین بر اساس مدل­های ون­گنوختن، بروکس- کوری و کمپبل برآورد شد. بعلاوه هدایت هیدرولیکی غیر اشباع به عنوان تابعی از پتانسیل ماتریک خاک به­وسیله­ مدل­های معلم- ون­گنوختن، معلم­- بروکس­- کوری، بوردین­- بروکس- کوری و کمپبل تعیین شد. مقدار پارامترهای توزیع تخلخل و پارامترهای نقطه ورود هوا در سیستم دو فازی بنزین- هوا نسبت به آب- هوا افزایش یافت. نتایج نشان داد به دلیل کشش سطحی کمتر بنزین، در مقدار معینی از فاز مایع، مکش کمتری برای خارج کردن بنزین از خاک نسبت به آب لازم است. بنابراین خاک در یک مقدار معین از فاز مایع، نگهداشت کمتری برای بنزین نسبت به آب دارد. همچنین مقیاس­سازی منحنی نگهداشت بنزین به صورت مناسبی بر مبنای تابع مقیاسی لورت انجام شد.  به دلیل لزوجت کم بنزین، هدایت هیدرولیکی اشباع محیط برای بنزین بیشتر از آب بود. لیکن در مکش­های بیشتر از حدود 30 سانتی­متر آب، هدایت هیدرولیکی محیط برای آب بیشتر بود.

کلیدواژه‌ها


عنوان مقاله [English]

Parametric Investigation of Soil Retention Functions in Two-Phase NAPL-Air System

چکیده [English]

In order to examine hydraulic behavior of LNAPLs in soil, the soil retention and hydraulic conductivity curves for gasoline and water were determined using hanging column and constant head methods, respectively. The soil retention parameters were obtained based on van Genuchten, Brooks-Corey and Campbell’s models. In addition, the soil hydraulic conductivity for both fluids were predicted based on Mualem- Brooks-Corey, Burdine- Brooks-Corey, Mualem-van Genuchten and Campbell’s functions. The results indicated that the magnitudes of the pore-size distribution parameters and the bubbling pressure parameters were increased in gasoline-air system compared to water-air system. Gasoline was retained less than water owing to its negligible surface tension, yielding less needed tension to drain gasoline out from soils. The scaling of soil-gasoline retention curve was reasonably accomplished via Levrett J-function. Due to insignificant gasoline kinematic viscosity, the saturated soil hydraulic conductivity for gasoline was higher than that for water. However, under unsaturated condition soil hydraulic conductivity for gasoline was less than that for water by increasing the matric head more than approximately 30 cm water.

کلیدواژه‌ها [English]

  • gasoline
  • Scaling functions
  • Soil hydraulic models
  • Soil retention curve
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