Influence Analysis of Calculated Horizontally Layered Soil Parameters on Grounding Parameters

Calculated parameters (soil layer resistivity, soil layer thickness, the number of soil layers) of horizontally layered soil are usually obtained based on the measured apparent resistivity under different measurement distances, which are significant for the design, operation, and maintenance of the grounding grid. Most existing calculation methods of soil parameters are just trying to make the calculation results approach to the measurement data, ignoring the relationship among measurement data, the calculated soil parameters and grounding parameters. Massive measurement data of large distance would contain more information about deep soils, but it would cause large measurement workload. However, when the deep soil does not have much influence on the grounding parameters, the massive measurement data is not necessary. To better balance the distance range of the measurement data and the influence of the calculated horizontally layered soil on grounding parameters, this paper systematically studies the relationship among measured apparent soil resistivity, calculated horizontally layered soil parameters and grounding parameters. The basic theories of apparent resistivity measurement, soil parameters calculation, and grounding parameters calculation are given, the influence of soil layer thickness on the measured apparent resistivity is studied, and the influence of the calculated soil parameters on the grounding resistance of different grounding models is analyzed. The results give the standard to judge whether the calculated soil is accurate and the strategies to choose the measured apparent soil resistivity for getting accurate calculated soil paramters. The contribution of this paper can provide a theoretical basis for the fast and accurate calculation of grounding parameters in practical engineering, which has far-reaching engineering significance.