Study On The Application Of Electrucal Resistivity Method In Evaluation And Reinforcement For Contaminated Soils

This paper is consisted of three parts, firstly, through the experimental study on electrical resistivity characterization of contaminated soil near the Yangzi River in NanJing, the relationship between electrical resistivity, formation factor, shape factor and its water content, void ratio, type and concentration of contaminated component and temperature et al is found. And the relationship between electrical resistivity, formation factor, shape factor of heavy metal contaminated soil and concentration is studied in detail. Furthermore , the principle and process of evaluating contaminated soil using electrical resistivity method are explained, at the same time, we have set up the evaluating standard for electrical resistivity suit to experimental site. Secondly, through study on the contaminant transport model, the principle of migration of contamination component in groundwater is opened out, besides, the dominating formulas and the analytical solutions for pure diffusion and advective-diffusion of contaminant transport are presented in this paper. And that finite layer analysis in one and two dimensions is carried through laplace transforms, in the end, numerical simulation of experimental site is put up and the change of contaminant within 200 years is forecasted. The third part of this paper is experimental study on the character of electrical resistivity of soil-cement. In this part the relationship between electrical resistivity and the cement-mixing ratio, water content, degree of saturation, water-cement ratio, curing time and strength is studied is studied. Also, the change trend for strength and permeability of soil-cement after pollution is explained. So the main research results are as follows:(1) The electrical resistivity, formation factor and shape factor decrease with increase of water content. The higher the water content is, the littler the change extent of electrical resistivity and formation factor are, but shape factor change little with different water content. Electrical resistivity and formation fall with accretion of void ratio, however, the relationship between shape factor and void ratio is different. When contaminant concentration is smaller than 0.3%, shape factor decreases with increase of void ratio, but when contaminant concentration is greater than 0.3%, shape factor hoists with increase of void ratio. At the same time, the more serious the soils pollute, the lower electrical resistivity is, and the higher formation factor and shape are. All of three depresses with rise of temperature.(2) For this experimental site, using electrical resistivity and formation factor can test contaminated soil when water content is lower. When water content becomes higher, electrical resistivity and formation factor will change little, so the test result is not very good. But formation factor method can extend the test scope and it work better when water content is lower. Shape factor method is suitable for all the water content, and the test result is better than other methods. However, in the some time, the small distance between serious contaminated line and moderate contaminated line is happened, so when testing contaminated soil, we should take into count all the three factors. For the soil whose contaminant concentration is very high, all the methods don't work very well, the main reason is that they change very litter in this situation.(3) The main contaminant transport models are advective transport, diffusive transport, dispersion and sorption. When coefficient of permeability or hydraulic gradient is too small, groundwater flows slowly even no flow, the main way of contaminant transport is diffusive in this circumstance. When encountering strong aquifer during contaminant transport, dispersion is happened. In the engineering application, we can use the similar way to calculate diffusion and...