Study on the Electrical Conductivity Characteristics and Modeling of Sand Considering Particle Morphology

The electrical resistivity of geotechnical media is influenced by various factors, with pore structure characteristics related to particle morphology playing a key role in resistivity parameterization. Existing studies are mostly theoretical and based on idealized assumptions, often limited by incomplete morphological descriptors, unclear mechanisms, and measurement difficulties. This study investigates five types of sands with typical particle shapes. Using morphological analysis and four-electrode resistivity testing, the correlations between 2D morphological features and resistivity parameters were examined, alongside micro-scale mechanism analysis. Results show that aspect ratio, convexity, roundness, and sphericity approximately follow normal distributions, with expected values effectively representing particle shape. Under normalized saturation and porosity, all sands exhibit similar trends: resistivity decreases with increasing saturation and porosity, following a power-law relationship. Resistivity parameters also correlate with the average morphological factor (Am) via power functions. At the same porosity and saturation, higher particle roundness enhances conductivity by reducing the tortuosity of pore water paths. Moreover, resistivity differences among sands diminish as saturation and porosity increase. A morphology-informed correction model is proposed and validated against the Archie and H-B models, showing improved accuracy and applicability. The findings provide theoretical and experimental support for understanding sand conductivity and advancing resistivity-based methods in geotechnical engineering.