磷石膏渗滤液在不同渗漏运移模式下电阻率分布特征

Resistivity of phosphogypsum leachate under different leakag-e migration modes

为评估电阻率法监测磷石膏堆场渗滤液运移过程的有效性,首先采用自制电阻率四极装置测试渗滤液污染土的电性特征,随后针对表层单点渗漏、内部岩溶管道多点渗漏2种模型开展不同时段渗滤液运移监测物理模拟实验,并加入岩溶水进行空白对照实验。结果表明,渗滤液及其污染土电阻率随渗滤液浓度增加呈递减趋势,且低浓度区间变化更为剧烈;在表层单点入渗过程中,渗滤液主要进行横向运移,并逐步形成漏斗状渗漏形态,而管道渗漏模式下渗滤液以四周扩散方式运移;加入岩溶水后,借助电阻率差异能够区分相同含水率下的污染区与未污染区;最后借助一种常用的电阻率法——高密度电法(ERT)对贵州省某磷石膏堆场进行实测,得到的低阻体范围与堆场位置存在较好对应关系,验证了前述实验结果。电阻率法可用于监测磷石膏堆场渗滤液在地表及地下管道内的渗漏过程及污染分布。

In order to evaluate the effectiveness of resistivity method in monitoring the migration process of leachate in phosphogypsum yard, a self-made resistivity quadrupole device was used to test the electrical characteristics of leachate-contaminated soil. Then, physical simulation experiments of leachate migration monitoring in different periods were carried out for two models: single point leakage of soil surface and multipoint leakage of karst pipeline, and karst water was added for blank control experiment. The results showed that the resistivity of leachate and its contaminated soil decreased with the increase of leachate concentration, and the change was more intense in the low concentration range. In the process of surface single point infiltration, the leachate mainly migrated horizontally and gradually formed a funnel-shaped leakage pattern, while the leachate migrated in a peripheral diffusion mode under the pipeline leakage mode. After adding karst water, the polluted area and unpolluted area under the same water content could be distinguished by resistivity difference. Finally, a common resistivity method, electrical resistivity tomography(ERT) was used to measure a phosphogypsum yard in Guizhou Province. The range of low resistivity body obtained had a good correspondence with the location of the yard, which verified the above experimental results. The study showed that the resistivity method can be used to monitor the leakage process and pollution distribution of leachate in phosphogypsum yard.