Experimental Study on the Soil Electrical Conductivity and Dielectric Constant Properties

Abstract Wireless monitoring can effectively enhance the operational safety of underground infrastructures. The electrical conductivity and dielectric constant of soil determine the transmission performance of buried wireless signals. To solve the problem of wireless monitoring signal transmission of underground infrastructure, the variation patterns of soil electrical conductivity and dielectric constant need to be explored. In this study, the effect of different particle size distribution, water content, and dry density on soil conductivity and dielectric constant were investigated by experiments. And the existing soil water content-resistivity and soil water content-dielectric constant models were evaluated and analyzed. The results show that both soil conductivity and dielectric constant increase with increasing water content and soil dry density, but the rate of increase first increases and then decreases with the increase of water content. Due to the varying complexity of surface charges on soils with different particle sizes, the high content of clay and silt with small particle size is helpful to improve soil conductivity and dielectric constant, while the increase of sand content with large particle size leads to the decrease of both. And the sensitivity analysis revealed that soil particle size distribution significantly affects the water content-resistivity and water content-dielectric constant relationship, whereas the impact of dry density is minimal. Based on the experimental data, the existing relational models were evaluated and analyzed. The median particle size (D50) is incorporated into the empirical model to elucidate the physical significance of the model parameters and to develop modified models. The modified models were validated using published data, demonstrating their good accuracy.