Soil conductivity will directly determine the stability of grounding system, and the cost of grounding system will vary up to 100 times due to the difference of soil resistivity in different areas under the same grounding resistance. Soil, as a porous medium, has a large number of pores between solid mineral particles, and ions can migrate through the channels formed by pore water, thus forming electric currents. Existing studies have found that the resistivity of the soil will change constantly with the change of water content, and there is a mutation phenomenon, but considering the soil water conductivity is highest, so can only guess at mutation reason is caused by the connectivity of water distribution. In this paper, MATLAB software was used to write a program to establish a soil fractal model, and then ANSYS simulation software was used to solve the problem, so as to analyze the conductivity of the soil model, and statistical analysis of the apparent conductivity of water micro-element in the soil and study its distribution in the soil model. In addition, the connectivity of soil resistivity at different times before and after the mutation was further studied and the number of cells contained in the conduction path of soil was counted. By controlling the variation of soil water content parameter, the distribution of cell number in soil conduction path in each column of soil model was studied. It was found that with the increase of soil water content, the distribution range of cell number in each column increased, and the fluctuation of numerical value decreased significantly. Therefore, the mean value and variance were introduced to analyze the variation rule of data. On the basis of this study, the influence of porosity on soil conductive path can be studied by changing the size of porosity.

Grounding;Soil conductivity;porous media;fractal