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为了全面准确的监测轻非水相液体(LNAPL)在非均质多孔介质中的入渗过程,本文通过室内试验模拟了LNAPL污染物在三维非均质砂槽中的运移,并采用高密度电阻率成像法获得电阻率值随时间的变化过程图.试验结果表明,通过三维电阻率值随时间的变化过程图清晰地反映了LNAPL在非均质多孔介质中的运移过程.在水平方向上,LNAPL污染的中心区域近似为圆形,随着LNAPL的注入量不断增加,被污染区域的范围不断增大,中心区域的电阻率值也不断增大.在垂直方向上,起初的污染区域近似为半圆形,当LNAPL接近介质的突变面时,污染区域的形状从半圆形变为了半椭圆形,即LNAPL的横向运移速度大于纵向运移速度,这种现象说明了位于砂槽中间的细砂透镜体对LNAPL的纵向运移起了阻滞作用,同时使其横向运移速度增大.通过高密度电阻率成像法得到的非均质电阻率值变化图可知,采用高密度电阻率成像法对非均质多孔介质中轻非水相液体的运移进行三维的、动态的监测是可行和有效的.
In order to comprehensively and accurately monitor the infiltration of light non-aqueous liquid (LNAPL) in heterogeneous porous media, this paper simulates the migration of LNAPL pollutants in three-dimensional heterogeneous sand tank through laboratory experiments and adopts high density Resistivity imaging method was used to obtain the change of resistivity value with time.Experimental results show that the process of LNAPL migration in heterogeneous porous media can be clearly reflected by the process of three-dimensional resistivity change over time. , The central area of LNAPL pollution is approximately circular, and as the injection volume of LNAPL increases, the range of contaminated area increases and the resistivity value of central area increases continuously. In the vertical direction, the initial contaminated area When the LNAPL approaches the abrupt surface of the medium, the shape of the contaminated area changes from a semicircle to a semi-elliptical shape, that is, the lateral transport speed of the LNAPL is greater than the longitudinal transport speed. This phenomenon shows that in the sand tank In the middle of the fine sand lens body LNAPL longitudinal migration has played a blocking role, while allowing lateral migration speed increases.High-density resistivity imaging obtained heterogeneous resistivity value changes we can see the use of Resistivity tomography method in heterogeneous porous media in the light non-aqueous phase liquid transport in a three-dimensional dynamic monitoring is feasible and effective.