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电容成像法是根据被测物质各相具有不同的介电常数,当各相组分分布或浓度发生变化时,将引起被测介质介电常数发生变化,从而使测量电极对间的电容值发生变化。以这些电容测量值作为投影数据,通过一定的图像重建算法,便可以获得介电常数分布,从而获得物质分布的图像。本研究运用电容成像法对NaCl溶液运移过程进行了实时监测,首先通过小砂盒进行了用不同浓度NaCl溶液饱和的多孔介质测定,得到了电容标定曲线,从而说明了电容成像法的有效性,然后通过砂槽进行了非饱和带中NaCl溶液的运移试验,并利用电容成像法进行了同步的动态监测,得到横纵向电容时间变化曲线,以及影像图,并通过三维电容相对值变化明显的看出NaCl溶液运移过程。这说明利用电容成像法对非饱和多孔介质中NaCl溶液的空间分布范围进行圈定并监测其迁移过程是完全可行的。
Capacitance imaging method is based on the measured material has a different dielectric constant of each phase, when the phase distribution or concentration changes will cause the dielectric constant of the measured medium changes, so that the capacitance between the measurement electrode pairs occur Variety. With these capacitance measurements as projection data, through a certain image reconstruction algorithm, you can get the dielectric constant distribution, so as to obtain the material distribution of the image. In this study, the migration process of NaCl solution was monitored in real time by capacitance imaging. First, the porous media with different concentrations of NaCl solution was used to measure the migration of NaCl solution. The calibration curves of capacitance were obtained. The validity of capacitance imaging method was demonstrated, Then, the migration experiment of NaCl solution in unsaturated zone was carried out by sand tank. The synchronous dynamic monitoring by capacitance imaging method was used to obtain the time-varying curve of transverse and longitudinal capacitance as well as the image, and the change of relative value of three-dimensional capacitance was obvious See the NaCl solution migration process. This shows that it is feasible to delineate the spatial distribution of NaCl solution in unsaturated porous media by using capacitance imaging and monitor its migration process.