Study On Time - Domain Combined Inversion Algorithm For Chromium Contaminated Soil Based On Cole - Cole Model

At present, China is suffering from serious heavy metal contamination of the soil, theoverall performance is: elements of the contamination tends to be diversified, pollution areawider and pollution levels increased, these problems have severely affected the nationalsustainable development of agriculture and industry, but also to life and health risk of human andanimal. Therefore, it is urgent to repair heavy metal contaminated sites, in doing this before, wemust to define the specific scope and the degree of contamination of the site, but also for soilsample analysis of the geological conditions, which requires pollution detection work.Traditional method is drilling, sampling and analysis of indoor chemical pollution detection,drilling and sampling can be broadly define pollution scope, but under the influence ofgeological conditions, the accuracy cannot be guaranteed, but also wasted a lot of manpower andmaterial resources; chemical analysis of the type of contamination and pollution levels isaccurate, but it also waste a lot of time. In short, the inefficiency of these methods led to heavymetal pollution field exploration work conducted in our country. Complex resistivity is widelyused as a detection method in geophysical field, but there are few researches in soil resistivity. Inthis paper, the method is applied to the detection of chromium metal contaminated soil werestudied, including Cole-Cole model parameters fitting method of research, which verifies thevalidity of the Cole-Cole model as a soil model. At the same time, it is also providing the basis toestablish quantitative relationships between soil physical parameters and Cole-Cole modelparameters, and promotes the practical application of detection of heavy metal pollution.Changes of chromium-contaminated soil’s physical parameters will cause the change of theelectrical parameters of soil, the discovery of the inner relationship between electrical parametersand physical parameters, which will give heavy metal contaminated sites to detect and repairwork to bring a huge boost. Research on chromium metal contaminated sites has been carried outfor many years. Based on the research of Liu Hao Rui et al, continue to select complex resistivitymethod as a method of detecting chromium-contaminated soil, select Cole-Cole model as acircuit model of soil. Using the time-frequency domain measurement method combinedcollection of experimental data, obtained four components of complex resistivity of the soil fromthe frequency domain measurements, obtained from the time-domain measurements of DCresistivity and charging rate as a priori data, fitting Cole-Cole model parameters, and thenverifies the validity of the model.Fitting of the Cole-Cole model parameters is at the heart of this paper. We use of simulatedannealing algorithm for parameter fitting. Popular, the algorithm simulates the method of solid annealing to solve the minimum value of the function, it is suitable for solving large scalecombinatorial optimization problem, The algorithm does not depend on the initial solution andsimple description of the characteristics, flexible parameter settings, and it has the advantages ofhigh efficiency and can reach global optimum. And for complex resistivity data fittingparameters, the algorithm can guarantee a solution for the real value of parameters from thefundamental requirements. For best results, this paper also presents an improved algorithm of thesimulated annealing algorithm, and introduced a genetic algorithm crossover and mutation ideas.The combination of simulated annealing and genetic algorithms effectively overcomes theproblems of simulated annealing search efficiency gradually reduced, also overcame thepremature phenomena of genetic algorithms, making further improvement in results.The main contents of this paper includes: the first chapter introduces the status of heavymetal pollution of the soil, discusses the necessity of chrome metal detecting in contaminatedsites, summarizes the pollution status of the detection technology, in the end, it concludes with athought and main content of this paper. The second chapter introduced the soil polarizationtheory, which provides a theoretical basis for electrical measurement, and take the Cole-Colemodel of rock resistivity as the circuit model of soil’s resistivity, and based on conclusions ofexisting research, physical meaning of the Cole-Cole model parameter is introduced in detail;The third chapter is the research about the chromium-contaminated soil Characteristics ofcomplex resistivity, including experiment content and method, and an analysis of the soilcharacteristics of complex resistivity results. The fourth chapter is parameter fitting which basedon soil complex resistivity model’s inversion, includes study of simulated annealing algorithmand the improvements of simulated annealing algorithm, the latter got the better parameter fittingresults, and fitting results to verify the validity and stability of the Cole-Cole model. The sixthchapter summarized the main contents of the paper, and the prospect of research work in thefuture.