城市垃圾填埋场地下渗滤液迁移模拟及电性响应

Simulation of Landfill Leachate Migration and Electrical Response in Urban Landfill Sites

城市垃圾填埋后,降水或地下水往往对垃圾产生淋滤作用,使得垃圾中的污染物溶解或悬浮于渗滤液中,易造成二次污染,因此,检测渗滤液污染范围成为了亟需解决的问题.以武汉市长山口垃圾填埋场渗滤液为研究对象,基于地下介质的物理和化学性质变化特征,采用高密度电阻率测深法监测受污染区域范围及扩散规律,利用化学元素分析方法探究产生电性差异的原因,开展不同时空的渗滤液迁移监测物理模拟研究.结果表明:(1)同体积的不同液体(填埋场渗滤液、自来水)在迁移过程中,在同一时刻相同位置渗滤液污染的土壤视电阻率明显比自来水浸入的小得多,其量值为自来水的1/5左右.(2)通过对渗滤液样品的导电粒子分析发现,污染土壤出现的较低电阻率主要是渗滤液中存在的多种导电粒子所引起.(3)渗滤液扩散过程可以分为2个阶段.渗漏初期,污染液主要是作横向迁移,此时采用电阻率测深法可有利于快速检测出渗漏点位置并加以防治,从而减少损失;渗漏中后期,渗漏点周围土壤含水饱和,渗滤液加速向下迁移并扩散至深部原始地层.研究显示,电阻率测深法可有效地监测渗滤液迁移、划分和评价土壤污染程度.

After the landfilling of municipal waste,leaching with rainfall or groundwater often causes secondary pollution because the pollutants in garbage can be dissolved or suspended in the leachate. Monitoring the migration of leachate has become an urgent problem. In order to monitor the migration of leachate at different times and in different spaces with physical simulation studies we conducted a study on the landfill leachate from Changshankou waste plant in Wuhan City. Based on the characteristics of physical and chemical properties of underground media,a high density resistivity method was used to detect the extent of the contaminated area and the diffusion mechanism.The chemical element analysis method was used to explore the reasons for the differences in electrical properties. The research indicated：（1） Given the same volume,the resistivity of soil contaminated by landfill leachate was significantly smaller than that of the soil with tap water in the same position at the same time.（2） The analysis of conductive particles of leachate indicated that lower resistivity of the contaminated soil was mainly caused by a variety of conductive particles which mainly exist in the leachate.（3） The leachate diffusion process can be divided into two phases. In the first stage of leakage pollutants mainly migrate laterally,in that case,using the resistivity sounding method can facilitate rapidly monitoring the leakage point and reduce losses; In the second stage of leakage,because the soil around leakage point is saturated,the pollutants migrate downward and diffuse into underlying strata. Our study showed that the resistivity sounding method is an effective method to monitor leachate migration and to classify and evaluate contaminated soil.