Investigation On Typical Electrical Resistivity Model Of Domestic Landfill-leachate Contaminated Soil

The contamination from domestic landfill-leachate has become a global common environmental problem. Complex composition of pollutants in leachate contains BOD, COD, ammonia, metal ions, and solid particles and so on. The majority of pollutants are dissolved in pore water after permiating through the soil. Heavy metals and solid particles insoluble in water become parts of soil and result in electro conductibility increase of contaminated soil. Based on this, Electrical resistivity tomography (ERT) is a new detection method for contaminated areas prospecting and diffusion process monitoring and has achieved good results in the past 10 years. However, pollution content has not been obtained based on ERT. The reason is that the basic electrical equation for contaminated soil is not established and boundary conditions are not clear in the typical of multiple solutions of inverse problem solution. By leachate contaminated soil resistivity test, this Paper study the effect of different factors on contaminated soil resistivity quantitatively, establish mathematical models about contaminated soil resistivity and pollution content and investigate the method for obtaining pollution content with ERT.Thesis is divided into five chapters. The first chapter introduces the related research, content, technical line and acquired innovative findings. The second chapter introduces the electrical method and its implementation principle for the leachate pollution survey. By 120 group of uncontaminated and contaminated soil resistivity testing, the third chapter study resistivity variation in the process of leachate continuous pollution in sand of different particles size compositions and water contents. According to contaminated soil resistivity testing data, the main factors of contaminated soil resistivity changes is analysised based on the Archie formula and mathematical models about contaminated soil resistivity and pollution content is tried to established from the resitivity mechanism. Experimental results show that the conductivity of the watery soil increases with the good conduction multi-ingredient pollutant pollution. And the increasing range is relation with the kind of soil and initial water content. The range is smaller when the fine grain content is more and bigger when the initial water content is smaller. The pollution causes pore resistivity reduce, saturation increase and suspended substance leads to the electric conduction retardation which is the primary factor causes soil resistivity change. The leachate-contaminated soil resistivity model follows the Archie formula. The formula could be used to analyze the relation between contaminated soil resistivity and the pollutant content, but the process needs to grasp soil porosity, cemented coefficient characteristic parameters and Electric characteristics of primitive infiltration fluid. In chapter four, the conclusions of chapter three are proved by leachate pollution electricity monitoring testing.2D and 3D resistivity imaging method, as well as electrode probe rod method are used in the process of simulated soil leachate pollution. The soil resistivity and the leachate concentration are tested before and after soil contamination in seven preset positions. Based on the test results the ability to reflect the contaminated areas by 2D and 3D images and their reconstructions is analyzed. In chapter four, the conclusions of chapter three are proved by leachate pollution electricity monitoring testing.2D and 3D resistivity imaging method, as well as electrode probe rod method are used in the process of simulated soil leachate pollution. The soil resistivity and the leachate concentration are tested before and after soil contamination in seven preset positions. Based on the test results the ability to reflect the contaminated areas by 2D and 3D images and their reconstructions is analyzed. The applicability of resistance results testing through different ways, the feasibility of caculating leachate concentration in soil based on elec(?)rical measurement Results are also analyzed. The results shows that apparent resis(?)ivity anomalies profile have correspondence with contaminated area, but not unanimously. The reconstructive profile images have better reflection to contaminated area. Of the three methods, the results of electric resistivity are most exact by directly testing soil samples, which can also derive from the resistivity results tested by using electrical profiling and electrode probe rod methods through updating formulas. And the two results are very close. The domestic landfill-leachate contaminated soil resistivity formula established in this paper has strong applicability. The fifth chapter gives the paper's overall conclusions and further work.Theory of contaminated soil resistivity is developed in this paper, and the foundation has been established for realization of quantitative detection of underground pollution based on resistivity.