Frozen soil resistivity exhibits high sensitivity to temperature variations and ice-water distribution. The conversion of soil water content (SWC) and resistivity based on petrophysical relationships enables the characterization of spatial distribution and changes in freezing and thawing states. Monitoring ground resistivity is essential for understanding frozen soil structure and evaluating climate change and ecosystems. The previous studies demonstrate that estimating soil resistivity below zero degrees based on the empirical model has significant errors. This work proposes a capillary bundle fractal model for frozen soil resistivity estimation based on SWC hydrologic parameters. The fractal theory describes the geoelectrical features of frozen porous media through the variable pore geometry and representative elementary volume. The sensitivity analysis discusses the potential relationships between pore parameters, conductance components, and fractal geometric parameters within frozen soil resistivity and reconstructs the hysteresis separation of freeze-thaw processes. The field test application in the seasonal freeze-thaw monitoring site demonstrates that the estimated resistivity and experimental samples are consistent with the field monitoring resistivity data. By combining unified conceptual assumptions, we established the connection between electrical permeability and thermal conductivity, offering a basis for exploring coupled hydro-thermal mechanisms in frozen soil. The proposed model accurately estimates the variations in seasonal frozen resistivity, providing a reliable reference for quantitatively analyzing the mechanisms of freeze-thaw processes.

Widespread saline soils in Northwest China pose a serious threat to the region's ability to use infrastructure safely because they are prone to soil structure damage when subjected to external environmental fluctuations, which in turn affects the stability of the foundations for buildings. The non-destructive approach of measuring resistivity can be used to swiftly reflect the subsoil body's state and make assumptions about its safety. However, the electrical resistivity of the underground soil body can be used to quickly identify unstable areas because the resistivity is influenced by the water content, salt content, and structural characteristics of the soil body. To do this, it is necessary to understand the coupling relationship between various factors. In this study, we first constructed samples with various water, salt, and soil structure characteristics, and then used indoor tests, such as soil resistivity measurement and thermogravimetric analysis, to analyze the multiple factors affecting the resistivity characteristics of the soil. The relationship between soil resistivity and actual saline soil diseases in Northwest China was then further discussed in conjunction with the results of the indoor tests and analyses. subsequently, the resistivity and soil properties have been measured in the field at specific locations in Northwest China where railway roadbeds are diseased. The study's findings can theoretically support a deeper comprehension of the law and mechanism of soil resistivity change, as well as provide assistance for building infrastructure in Northwest China.

Grounding systems is a fundamental part in an electrical power engineering system. It is important for ensuring the safety of occupants, to protect electrical equipment from damage, minimize the risk of electrical hazards and maintain a stable system during both normal and fault conditions. Hence, a grounding system must provide a path for fault currents to safely dissipate into Earth while preventing electrical shock hazard, and reduce and limit the damage to any electrical equipment connected to it. However, traditional grounding systems may not always be able to provide the required level of conductivity, especially in high soil resistivity sites or in applications where high fault currents are anticipated. Resistivity of the surrounding soil is one of the parameters that can be easily manipulated for an efficient grounding system to be made available as it is influenced by factors such as geographical location, moisture content, temperature, and soil composition. In regions with poor natural soil conductivity or environments characterized by seasonal fluctuations in resistivity, the deployment of natural enhancement material is merged as a critical solution. In this work, three sites located around Universiti Putra Malaysia Serdang Campus, Selangor, MALAYSIA were tested for its soil resistivity. This is meant for grounding system installations with new natural enhancement material mixtures in the vicinity of vertical ground conductors. Site 2 with high resistivity and most homogeneous soil would be chosen to test the grounding system installations, while Site 1 with the lowest soil resistivity would be installed with Reference grounding system as comparison purposes. Note that a Reference grounding system is installed without any natural enhancement material mixture in the vicinity of the vertical ground conductor.